Ukraine has narrowed down the most likely cause of the plane crash that killed 176 people to either a missile hit or terrorism.
The country's state security chief Ivan Bakanov said the two possible avenues were being prioritised for investigation.
Foreign minister Vadym Prystaiko said Kiev was not ruling out any possible cause.
Canada and the US have said it is likely a missile hit the jet before it crashed. The British government has also indicated it believes that is the most likely scenario.
The nations have, however, suggested it was unintentional. Iran has rejected any possibility of blame and instead insisted there was an issue with the jet.
"We do not reject any of the versions," Mr Prystaiko said at a televised briefing in Kiev.
"We want to establish the truth.
"At the moment, we have no reason to say that the Iranian authorities are not coordinating their activities or are not sufficiently interacting with Ukraine."
Ukrainian flights to Iran and Iraq were banned until the investigation has been concluded, he said.
He added that the plane had changed course after an incident but it was hard to say what the reason was.
The Ukraine International Airlines flight to Kiev from Tehran crashed on Wednesday.
At that time, Iran was on alert for a possible US military response hours after firing missiles at US targets in Iraq.
Those killed in the crash included 82 from Iran, 63 Canadians, 11 Ukrainians, 10 Swedes, four British citizens and three Germans.
