Yeh, I was just curious, because in Dubai, they have a lot of tours to Iran. This is from the US Dept of State website.
IRAN, ISLAMIC REPUBLIC OF - *Passport and visa required. The United States does not maintain diplomatic or consular relations with Iran. Travel by U.S. citizens is not recommended. Attention: U.S. citizens need a Treasury Dept. license in order to engage in any transactions related to travel to and within Iran. Before planning any travel to Iran, U.S. citizens should contact the Licensing Division, Office of Foreign Assets Control, Department of the Treasury, 1331 G St., N.W., Washington, D.C. 20220 (202/622-2480) or
http://www.ustreas.gov/ofac/. For visa information, contact the Embassy of Pakistan, Iranian Interests Section, 2209 Wisconsin Ave., N.W., Washington, D.C. 20007 (202/965-4990). Internet:
http://www.daftar.org
I was wondering what the "license" mentioned was. No problem, have a good and safe trip.