Question: My friend has a few American visa stamps on her passport. Can she get into Iran? The consulate is close today so we couldn't ask it. She no needs visa according the visa act between her country and Iran.
Answer: Due to the rules dominating over Iran, not only Israeli nationals are not allowed to enter Iran but also the travelers to Israel are not authorized to get a visa to Iran while they have Israeli visa stamp in passport. Israel is the only county included in this rule and other countries even America and the neighboring countries to Israel are excluded of this rule, it means that having the visa stamp of those countries is not a barrier to get authorization of entering Iran.
For more information about Iran visa check: http://www.uppersia.com/Iran-travel-services/iran-visa.html