Spokesman Gholamhossein Esmaili said investigations into the incident were continuing, but provided no details.
President Hassan Rouhani said the probe would be overseen by a "special court".
Ukrainian International Airlines flight PS752 was brought down shortly it took off from Tehran on Wednesday, killing all 176 people on board.
Most of the victims were Iranian and Canadian citizens.
For the first three days after the crash, Iran denied that its armed forces had shot down the Boeing 737-800 and suggested there had been a technical failure.
But as evidence mounted, the Revolutionary Guards said the operator of a missile defence system had mistaken the aircraft for a US cruise missile and fired at it.
Iran's air defences had been on high alert because the country had just fired ballistic missiles at two US bases in Iraq, in retaliation for the killing of top Iranian general Qasem Soleimani in a US drone strike in Baghdad.
The admission of responsibility provoked widespread anger in Iran, and protesters took to the streets in the capital and several other cities to denounce government lies and the clerical leadership including Supreme Leader Ayatollah Ali Khamenei.