Well never having been to Iran, I wouldn't like to say how you will be treated. But I wouldn't expect any problems really. As long as you behave, are respectful to their culture, and don't expect to get alcohol in the airport, all should be fine.
Have you had a look on any of the booking sites in this sticky for alternative flights with better prices?
http://www.phuket-info.com/forums/ac...-thailand.html