U.S. Citizen Services
In the absence of diplomatic or consular relations of the United States of America with the Islamic Republic of Iran, the Swiss government, acting through its Embassy in Tehran, serves as the Protecting Power of the USA in Iran since 21 May 1980. The Swiss Embassy's Foreign Interests Section provides consular services to U.S. citizens living in or travelling to Iran.
The U.S. Department of State has issued a travel warning to American citizens who wish to travel to Iran. We advise you to review it if you intend to travel to Iran. It can be found here. More country specific information is also available here.