Speaking on state television on Wednesday, Iran's President Hassan Rouhani called upon the military to elaborate more on how it shot down a passenger plane by mistake.
In a separate statement, Mohammad Javad Zarif, the Iranian foreign minister, acknowledged that Iranians "were lied to" for days afterwards, reports the BBC.
The Iranian foreign minister 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.
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.
The Iranian president urged the forces "to explain to people what sessions and meetings were held since the moment the incident had happened".
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 the Western authorities claimed to have contrary evidence.
Flight PS752 was brought down after it took off from Tehran on January 8 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.
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.
What action has been taken?
Iran is leading the investigation domestically and has refused to hand over recovered black-box flight recorders to manufacturer Boeing or to the US.
Iran's judiciary spokesman, Gholamhossein Esmaili, announced on Tuesday that several people had been arrested.
In an apparent reference to the recent anti-government protests, he added that about 30 people had been detained for "taking part in illegal gatherings."
Also on Tuesday, President Rouhani said the investigation into the aircraft strikes would be overseen by a "special court" and insisted that it would be about more than just the person who "pulled the trigger".
Meanwhile, the Revolutionary Guards have also arrested the person who filmed footage that showed the plane being shot down.
The video was shared on social media soon after the crash, leading analysts to deduce that the plane was directly hit.
It is believed the person being detained will face charges related to national security. However, an Iranian journalist based in London who initially posted the footage has insisted that his source is safe, and that the Iranian authorities have arrested the wrong person.