A action movie possibly made in the 80s or 90s

All I can remember is a fight scene on top of a skyscraper at night, one man who for some reason was completely butt naked while fighting a gang of men in blue jeans and black jackets, I don't know why he was naked, some hitmen came to try and kill the guy, he ran upstairs onto the roof which is where the fight took place. The guy didn't get any time to put any clothes on and there might have been a sex scene before it and the film may have been set in LA. Hope someone can