Iran's President Hassan Rouhani has said the country's military should elaborate more on how it shot down a passenger plane by mistake last week.
Separately, Foreign Minister Mohammad Javad Zarif acknowledged that Iranians "were lied to" for days afterward.
He insisted that he and the president were also kept in the dark.
Iran's Revolutionary Guards killed 176 people when they "unintentionally" shot down the Ukrainian aircraft amid escalating tensions with the US.
Hours before, Iranian missiles had targeted two airbases in Iraq housing US forces.
Speaking on state television on Wednesday, President Rouhani called on the military to take the next steps of the investigation with "more coordination and monitoring".
"The first thing is to inform people honestly. People's grief will alleviate when they know that we feel responsible for what happened and talk with them honestly," he said.
He urged the forces "to explain to people what sessions and meetings were held since the moment that the incident happened".
Mr Zarif, during a televised interview while on a trip to India, said: "I and the president did not know [what brought the plane down] and, as soon as we did, we communicated it".
He also praised the military for being "brave enough to claim responsibility early on". However, critics have decried the three-day delay and said they only owned up after Western authorities claimed to have contrary evidence.
New footage - verified by the New York Times - shows two missiles, fired 30 seconds apart, striking the plane. It was initially thought to have been hit once.
Flight PS752 was brought down after it took off from the capital, Tehran, on 8 January, when the Revolutionary Guards - a force set up to defend Iran's Islamic system - mistakenly perceived it as a threat amid escalating conflict with the US. Everyone on board died.
The deaths and the apparent initial cover-up - when the act was denied and the crash site was bulldozed - have sparked protests in various Iranian cities.
Police in Tehran have been accused of using live ammunition against demonstrators.
Iran's Supreme Leader Ayatollah Ali Khamenei is expected to deliver Friday prayer sermons in the capital this week for the first time since 2013, in an apparent bid to ease domestic tension.
How has Iran's crisis unfolded?
Last Wednesday, Iran launched a series of strikes on two military bases in neighbouring Iraq, which were housing US troops. It was a retaliatory move after US President Donald Trump ordered a strike in Iraq that killed top Iranian General Qasam Soleimani
