The United States extended condolences on Wednesday to families of the 168 people feared killed in the crash of a Caspian Airlines plane in northwestern Iran, Reuters reported.
The United States has no diplomatic relation with Iran but has sought to reach out to the Iranian people as part of an effort to coax Tehran into negotiations over its disputed nuclear program.
"The United States extends it condolences to the families of those who lost their lives in today's crash of a Caspian Airlines plane carrying passengers from Tehran, Iran to Yerevan, Armenia," State Department spokesman Ian Kelly said in a statement.
The Caspian Airlines aircraft was traveling from Tehran to Yerevan when it went down on Wednesday morning near the city of Qazvin, the official Iranian news agency. IRNA, said.
News reports said the plane carried 153 passengers and 15 crew. IRNA quoted officials as saying the plane crashed 16 minutes after takeoff from Tehran's Imam Khomeini International airport and that everyone on board was killed.
Kelly said the State Department was working through the U.S. Embassy in Yerevan and the Swiss Protecting Power in Iran to determine whether any American citizens were on board.
Since taking office, President Barack Obama has made a series of overtures to Iran, including a videotaped New Year's message to the Iranian people.
The United States severed relations with Tehran 30 years ago during the 1979-1981 hostage crisis, in which a group of militant Iranian students held 52 U.S. diplomats hostage at the U.S. Embassy for 444 days.