A Ukrainian airplane carrying 180 passengers and crew crashed on Wednesday near an airport in Tehran, Iranian state TV reported.
There was no immediate word on casualties.
The plane had taken off from Imam Khomeini International Airport, the report said. The crash is suspected to have been caused by mechanical issues, it added, without elaborating.
An investigation team was at the site of the crash in southwestern outskirts of Tehran, civil aviation spokesman Reza Jafarzadeh said.
Flight data from the airport showed a Ukrainian 737-800 flown by Ukraine International Airlines took off Wednesday morning, then stopped sending data almost immediately afterward, according to website FlightRadar24. The airline did not immediately respond to a request for comment.
The crash came hours after Iran launched a ballistic missile attack targeting two bases in Iraq housing US forces in retaliation for the killing of Revolutionary Guard General Qassem Soleimani.