Iran Civil Aviation Organization chief Ali Abedzadeh said "terrorism" had played no role in the crash, the BBC reported citing Iranian Mehr news agency.
Another official, Qasem Biniaz, blamed an engine fire. "Had the accident happened due to a missile strike, the plane would have exploded in the air," he told the IRNA news agency.
A Kiev-bound Ukrainian Boeing 737 passenger plane with 179 people on board crashed on Wednesday shortly after taking off from the Iranian capital of Tehran, killing all those aboard.
The number of people on board had differed and also the toll was initially said to be 176.
But the head of Iran's Emergency Medical Services, Pir-Hossein Koulivand, confirmed the latest toll saying that there had been 170 passengers, including 147 Iran, and nine crew members on the Ukraine International Airlines flight PS752 that went down in the vicinity of Parand, a city in Robat Karim county, reports Press TV.
Ukrainian President Volodymyr Zelensky ordered the creation of a crisis team to handle the accident, including top ministers and managed by the country's national security agency.
"We have prepared emergency planes to send to Tehran... to fly out the bodies of the victims, we are waiting a confirmation by Iran for their departure,"
Ukrainian Foreign Minister Vadym Prystaiko said that the victims were 82 Iran, 63 Canad, 11 Ukrain including all the crew, 10 Swedes, four Afghans, three Britons and three Germans.
Ukraine International Airlines has suspended flights to Tehran indefinitely.
( With inputs from IANS )