I've been there - theres some climbing/bouldering north of teheran (you can leave your hotel in the morning and be back in the eveneing). it's called darband. i ran into many climbers / blouderers - all very friendly (like everybody in iran) and wanting to climb/belay. I even could use their shoes etc.
then there's a big multipitch in the north - where the annual climbing festival takes place. there a good report with routes (and probably contact names) in VERTICAL MAGAZINE - download the app http://www.vertical-magazine.com/version-ipad-iphone and check the back issues...I forgot which issue. worth reading!
I'm planning to go back this year...such a good place. In case you've never been there...I made a video..to give you some impressions: http://www.vimeo.com/12235829
The climbing in Iran is ace, i just can't remember where we went at all, spent a month there doing various stuff. Its super hot though depending when you go. We were there in July (thats why it was hot!)
We went to some awesome place in the middle of the desert with 6 pitch bolted routes,
You could send Parsa on here a PM. He is Iranian and is always helpful. If you go, send me a PM and I'll give you a contact for a friend of mine who lives north of Tehran. He isn't a climber but he's a great guy and may be good for general travel advice.
I went to Iran in September to do Damavand. Not climbing as such, so no idea about where is best. They have a national mountaineering council or association who run some climbing walls though who might be able to help you.
Getting a visa isn't straightforward - we've closed their embassy and they ours, so you need to go to France or Dublin, costs a fair bit as well. Other than that, keep away from the Basijis and watch out for Israeli war planes etc.