“We have 250 planes in the country, 230 need to be replaced,” said Ali Abedzadeh, the head of the civil aviation body, adding that the deal still needed approval from the US government.
In an interview with the Iran daily newspaper, Abedzadeh said there could be no precise timeline for the contract without US Treasury permission.
Boeing confirmed on Wednesday that it was in talks with Iranian airlines interested in buying its passenger planes.
In February, the American company was granted approval from the US government to explore resuming sales to Iran after US sanctions were partially lifted in January following a deal on Tehran’s nuclear programme.
Boeing has requested final authorisation from the US Treasury for the sale of aircraft, Abedzadeh continued.
He said the reported value of $17 billion (15 billion euros) for the contract was not final and that more details will be provided after further negotiations.
Iran in January reached a memorandum of understanding with European aircraft manufacturer Airbus for the purchase of 118 planes.
That agreement is still pending permission from the US Treasury.
Airbus needs the approval of OFAC (the US Office of Foreign Assets Control) because more than 10 percent of Airbus components are of American origin.