Thought I'd add some of my experiences to this since it was off the main tourist trail! Overall the Iranians are friendly people. But.
In Alīgūdarz (west of Esfahan, taken that route to avoid the nuclear facilities!) I had stopped in a small park on the main road to wait for my friend to catch up. While there as usual a car stopped, backed up to look at the bike and then they called out from the car in farsi, I call back "Farsi balad neesam", but they persist in trying to talk. One of them came over and tried talking more so I told him no farsi again, then he tried to grab for my phone which was in my hands at the time (I was checking a map). I mistook that for the usual friendly iranian way of trying to communicate but he made a few more grabs for it but I held on tight. Then he gave up, walked back around the bike, unzipped the tank bag and took out the spot messenger and ran for the car. As soon as I saw him unzip the bag I got up and ran over but I was only able to touch the door as it sped off. The idiot took the only thing that alerts myself or authorities to it's location, no huge problem except now I can't let people know I'm OK. As I'm packing up to get out of there they appear again. This time they hold the spot messenger out the window and I think they want me to go get it, I don't leave the bike because they probably want me off it and then a nearby kid gets it and hands it back to me. I guess they didn't know what it was for? Who knows. They didn't take the GPS or notice that the keys were still in the bike, which was lucky. I was glad I had it back a few days later to let people know I was OK after the earthquake in Tabriz!
In Qeydār, again, I stopped to let my friend catch up. This time a bike stops with two guys on it, they persist in talking in farsi no matter how many times I say no farsi. This time I'm wise to what happened before so I'm still sitting on the bike and the tank bag has a padlock on it. But they're pointing at different parts of the bike, still asking questions in farsi, eventually getting to the back of the bike and looking at stuff there. A car had pulled up beside me so now these guys are out of my vision and the guy in the car just gave up after asking if I speak farsi. Then I see one guy start the bike they had, and the other running to get on the back with his hands under his shirt. I check behind me and sure enough the cap of the PVC pipe I have there is lose. All they've taken is an aluminium water bottle but I'm quite annoyed that another incident like this has happened within a few days. And as per last time, THEY CAME BACK. I made it known to the larger group around me now that they were not welcome back.
Lesson learnt? If they persist in talking farsi to you they're going to rob you. Every other person in Iran gave up after learning we didn't speak the language.
So be wary, the overly friendly people can disarm you, for the most part people are great though.