Dunno about punk under Khomeini, but there was some pretty good political folk rock in the 70s. A friend of mine was a supporter of the Fedai (one of the Communist parties) and had a fair bit of it. I couldn't name any performers though.

The highest profile oppositional musician today (at least, as seen from here) is probably Kayhan Kalhor. But the music that will be having an effect internally will be harder to find - I can ask. But I'm more interested in the traditional stuff anyway.