The two black boxes from the Ukrainian airliner that crashed outside the capital Tehran were found on Wednesday, Iranian state television reported.
An Iranian official was quoted as saying both boxes were damaged but that it was believed their data could still be retrieved.
The Ukraine International Airlines Boeing 737 flight PS752 crashed shortly after takeoff from Tehran on Wednesday, killing all 176 people aboard shortly after taking off from Tehran’s Imam Khomeini airport.
Iran's aviation authority however said it would not hand over to Americans the recovered black boxes.
"We will not give the black boxes to the manufacturer (Boeing) and the Americans," Iran Civil Aviation Organisation head Ali Abedzadeh said, quoted by Mehr news agency.
"It's not yet clear which country the black box will go to for the investigation," he added.
Abedzadeh said that based on global aviation rules, it was the right of the country where air crashes occur to carry out the investigation.
"This accident will be investigated by Iran's aviation organisation but the Ukrainians can also be present during the incident's investigation," he added.
Under the rules of the International Civil Aviation Organisation, of which Iran, Ukraine and the United States are all members, air crash investigations are led by the country where the accident occurred.
However, according to aviation experts, the countries that are capable of analysing black boxes are few -- notably Britain, France, Germany and the United States.
France's Accident Investigation Bureau (BEA), which handles air crash investigations, said it had not received any request for help from the Iranian authorities after Wednesday's crash.