This is a compilation of the quotes of Srila Prabhupada on 'miniskirt':

Srila Prabhupada: ...People are trying sense gratification in so many ways, and now they have come to the last point: the naked dance and... what is that short skirt? 
Devotee: Miniskirt.
Srila Prabhupada: Miniskirt, yes. [Laughs.] So, because in the material world the basic principle is sex, everyone is inviting, "Yes, come on, enjoy sex. Come on, enjoy sex." But no matter how you try to enjoy sex, you cannot be satisfied. That is certain, because sense gratification is not your real platform of enjoyment. You are a spirit soul, and unless you come to the spiritual platform you will never be satisfied by any sense gratification. You'll simply go on hankering after pleasure, but you will find no satisfaction.

(The Journey of Self Discovery 3: The Pleasure Principle- Liberation to a higher pleasure)

Prabhupada: Just like in hog civilization. That's all. They are thinking that "We are very happy eating stool." But others know that what kind of happiness he is enjoying. Similarly these rascal karmis, materialists, they are thinking by... What is called? Kini...What is called? Naked skirt?
Devotees: Miniskirt?
Prabhupada: Miniskirt, trying to show the private part and people will be attracted and she will be happy. This is regular prostitution. Regular prostitution. Still they are not getting husband. Even they walk naked... That will come. Say after fifty years it will come like that.
Syamasundara: They are starting already some places, walking naked.

(Room Conversation- 15th August 1971, London)

Dayananda: In America now, so many so-called cultured men, lawyers and doctors and so many cultured men, their language is very horrible, their...
Prabhupada: Vulgar.
Dayananda: Their whole attitude is vulgar also, not just language but whole... Yeah. And like even in Europe before, a gentleman was a gentleman. They were... I think. And even in America before, they had some good qualities. But now the so-called gentlemen or educated men, they're very vulgar.
Hrdayananda: Vicious.
Dayananda: Becoming more and more gross.
Prabhupada: Varna-sankara.
Dayananda: Yes. Like that.
Prabhupada: Therefore their sons are hippies.
Dayananda: Yes.
Prabhupada: The father is varna-sankara, the son is also.
Hari-sauri: The more vulgar you are, the more glorified you become, especially like all these film stars and public figures. The more of a drunkard they are, then the more they're publicized in the news.
Prabhupada: Just like John Lennon. He is a public man.
Dayananda: Yes.
Prabhupada: Just see. What he is? He's standing naked and taking photograph. His wife and he, standing naked. I have seen. And that picture is there in his sitting room, fireplace. That is the picture. (laughs) I went to see him. I was his guest. So one day I was... I saw there that big picture on the fireplace. And here is a public... Newspapermen go to him to take his opinion. "What is your opinion?" Just see. What is his value? Nobody... He is public leader because he has got some money. Money is the criterion. Therefore people are accumulating money some way or other. He knows that "If I got money, then I'll have all influence over the society."
Hari-sauri: A rich man no matter what his morals or character...
Prabhupada: No, nobody cares.
Hari-sauri: ...he becomes very attractive.
Prabhupada: Anyone who is not Krsna conscious, he has no good quality. Na mam duskrtino mudhah prapadyante naradhamah [Bg. 7.15]. These are the... From the Vedic angle of vision, the Western people are the most uncivilized. Only money is covering them. When they introduced that mini- skirt for the girl, how much abominable it was considered in India. But they very publicly introduced.

(Morning Walk- 27th February 1976, Mayapur)

The more you can decorate the Deities soberly, not fanatically, the more you become decorated with all honors. At the present moment, civilized man has forgotten how to decorate, therefore this mini-skirt—the business of the trees—to remain naked. Human being means to be decorated, like Krsna is decorated, not naked.

(Letter to Bhakta Das- 4th March 1973, Calcutta)

Prabhupada: So you say, "I accept (Baradraja repeating) Rukmini as my wife. I shall maintain her throughout my life, supply all necessities of life, and we shall work together for prosecuting Krsna consciousness." You say that "I accept you (Rukmini repeating) as my husband, and I shall serve you as your most obedient wife, to keep you in all comforts, in all distress and happiness, and we shall continue our life for Krsna consciousness." Now change. Change the garland. Mind that this promise has been made before Radha and Krsna. You cannot change all these promises. Change your seat. Cover the head. Cover the head and give her this red. Cover it nicely. You see, here. You should keep your wife always covered. (laughter) Don't allow this miniskirt or minishirt. (laughter) According to Vedic civilization, respectable woman cannot be seen even by the sun. Asuryam pasyat. How can you avoid sun? But it is said like that. The sun will find difficulty to see one man's woman. Yes. Asuryam pasyat. Asuryam. Surya means the sun. Sun cannot. Sun will also hanker after her: "How can I see that woman?" (chuckles) So woman should be always in privacy. They should be respectfully protected by the husband and the father. That is the way. All right. Then it is finished. Now let us perform yajna. (devotees offer obeisances) Now chant Hare Krsna. After performance of yajna. Chant Hare Krsna. Mix it. Mix it.

(Wedding Ceremony and Lecture- 6th May 1969, Boston)

Prabhupada: Miniskirt, yes. (laughs) So because here the basic principle only sex, everyone is inviting, "Yes, come on, sex. Come on, sex." But this way, that way, sex, anyway you enjoy, you cannot be satisfied. That is certain. Because that is not your platform of enjoyment. You are spirit soul. Unless you come to the spiritual platform, these material, any kind of sense enjoyment... Therefore you will never be satisfied. You'll simply hankering after, but there will be no satisfaction.

(Lecture- 13 November 1968, Los Angeles)

Prabhupada: Yes, this is the fact. We can see it. We can see it. That's all. Everywhere the same business. In the Western world they are becoming more and more naked. You see? Mini, miniskirt.
Dr. Patel: What they call it?
Bhagavata: Streaking.
Dr. Patel: No, no, no. What is that called, costume?
Prabhupada: Topless. Topless.
Dr. Patel: Topless and bottomless.
Prabhupada: These things are going on. That means they are attracted. Attracted. Pumsam striya mithuni-bhavam etad. They'll dress. Woman will dress very nicely so that she can attract man, and man will also do something which will, he'll attract woman. Mithuni-bhavam tayor mitha... In this way, when they are united-hrdaya-granthim ahuh, a very strong knot: "Oh, you are mine. I am yours." (laughter) "You are mine. I am yours." In this way they pull on this material life. And then, gradually, "Now we must have good apartment to live and enjoy sex life." Pumsam striya mithuni-bhavam etad tayor mithah hrdaya-granthim ahuh, tatha grha. "Now have skyscraper building." Ksetra: "Land. We must produce food grains." Tatha grha-ksetra-suta: "We must have children."

(Morning Walk Excerpts- 1 May 1974, Bombay)

Prabhupada: This is the veriya dasan. [break] ...taken the story from the Aesop's, no, Hitopadesa. Languli-hina srgala, a jackal without tail. So this is the world. Any nonsense you do and if you say, "It is the latest fashion," everyone will do. The miniskirt. One girl made it, so all girl. The veriya not only amongst the sheeps, and the so- called animal sheeps also do that, human sheeps. [break] ...very deep there, the water? They are standing.

(Morning Walk- 7th June 1975, Honolulu)

Prabhupada: So our gurukul should be ideal. Not all these boys... You should take care of these things from the very beginning—if you want actually spiritual life. If you want to progress like animals, that is different thing, as the whole world is doing. We want to maintain an ideal institution. People may see. In Christian idea also, the nuns were separate.
Tamala Krsna: Nowadays the nuns, every... Twice a week they get their hair set. They wear miniskirt now.
Prabhupada: And so many scandal.
Tamala Krsna: They're not strict anymore. Priests are smoking cigarettes, watching television.
Prabhupada: If there is no training, naturally it will deteriorate.

(Morning Conversation- 30th April 1977, Bombay)

Prabhupada: Human activity should be guided toward Krsna consciousness. Then it is human. Otherwise it is animal. Take minimum demand, be happy, and make progress. That is the platform of progress. Very little... (too faint) The same shape, (too faint) they are improving to make straighter, topless, bottomless, in this way and that way, miniskirt. They are arranging. The thing is the same, but they want to change the taste in different way. No knowledge. That means (too faint). Sex, you require under... You'll get it between husband and wife. There is no difficulty. What is the use of that? Daily pregnancy, daily... Three days divorce. Actually I saw in Chicago, within three weeks, three divorce.

(Conversations- 28 June 1977, Vrindavan)

One evening in Bhaktivedanta Manor in London, Srila Prabhupada was sitting in his room with his disciples and a few guests, including a woman reporter who had come to interview Srila Prabhupada. Despite the chilly English summer weather, the reporter was dressed in a scanty mini skirt. Her first few questions revealed her skeptical and almost cynical attitude toward the Hare Krishna movement. As usual, Srila Prabhupada coolly and expertly answered her questions. Somewhat exasperated and in a challenging mood, she brought up the old question, "Why do you people have bald heads?" Srila Prabhupada immediately retorted, "Why do you have bare legs?" She was speechless. Srila Prabhupada then offered, "Better to have warm legs and a cool head." Everyone, including the reporter, laughed with delight. Prabhupada added, "You must have a cool head to understand this Krishna consciousness philosophy." Yadubara dasa, interview.

(Reference: Srila Prabhupada's Nectar by Satsvarupa das Goswami)