The Aseman Airlines passenger plane came down in the Zagros mountains on Sunday, and all those on board are feared to have been killed.
Heavy wind and snow forced rescuers to stop the search late on Sunday.
The ATR 72-500 twin-engine turboprop was travelling from Tehran to the south-western city of Yasuj.
Flight EP3704 left Tehran at 04:30 GMT on Sunday, and crashed about an hour later on Dena Mountain, near the city of Semirom in Isfahan province.
The crash site is about 22km (14 miles) from Yasuj, Iranian media reported.
The crashed plane was 25 years old, Iran's civil aviation organisation said.
Search and rescue teams were dispatched to look for the wreckage, but were later forced to stop the operation.
"With the wind intensifying, and with snow, rain and darkness, it is not possible for rescue and relief teams to reach high altitudes and the search operation has been postponed until tomorrow," broadcaster IRIB announced.
"Five helicopters are on alert to resume the search at dawn if the weather conditions are better."
'God has been kind to me'
Sixty passengers, two security guards, two flight attendants and the pilot and co-pilot were on board.
Aseman Airline initially said everyone had been killed, but said later: "Given the special circumstances of the region, we still have no access to the spot of the crash and therefore we cannot accurately and definitely confirm the death of all passengers of this plane."
Passengers' relatives earlier gathered at a mosque near Tehran's Mehrabad airport, according to AFP news agency.
"I can't bring myself to believe it," said one woman whose husband was on the plane.
One man told Tabnak news website that he had missed the flight.
Showing an unused ticket as proof, he said: "God has been really kind to me but I am so sad from the bottom of my heart for all those dear ones who lost their lives."
Iran's President Hassan Rouhani expressed sympathy for all involved, saying in a statement that the incident brought "great grief and sorrow".
Iran has suffered several aviation accidents in recent years and has an ageing aircraft fleet.
The country has struggled to obtain spare parts to maintain its planes in the face of international sanctions imposed to curb its nuclear programme.
Those sanctions have been mostly lifted under a 2015 deal between Iran and the US alongside several other powers.
Aseman, Iran's third largest airline, signed a contract with Boeing last year to buy 30 of its latest medium-range 737s.
Iran's Supreme Leader, Ayatollah Ali Khamenei, has also expressed "deep sympathy" for relatives of those on board, saying the accident "saddened the hearts".
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