Ali Abedzadeh, the head of Iran's of Civil Aviation Organisation, said: "Scientifically, it is impossible that a missile hit the Ukrainian plane, and such rumours are illogical".
Canadian Prime Minister, Justin Trudeau has held the Iranian missile responsible for the incident that caused the crash of the Ukrainian International Airlines Boeing 737 at the Tehran airport.
Iran's state-run IRNA news agency quoted Foreign Ministry spokesman Abbas Mousavi as saying Iran "has invited both Ukraine and the Boeing company to participate in the investigations".
The plane crashed hours after Iran launched a series of missiles at an air base housing USA troops in Iraq.
Experts believe an Iranian surface-to-air missile hit the jet before it crashes in a ball of flames just minutes after take-off.
Sixty-three of them were Canadian citizens, including entire families, academics, students and newlyweds.
Western leaders say the plane appeared to have been unintentionally hit by an Iranian missile, just hours after Iran launched a series of ballistic missiles on two American bases in Iraq, in retaliation for the killing of its top general in a US airstrike. The official said the Boeing 737-800 had been tracked by Iranian radar.
The Iranian government said the missile strike scenario made "no sense", however, arguing that several internal and worldwide flights had been sharing approximately the same airspace.
Kiev has said its investigators wanted to search the crash site for any debris of a Russian-made missile used by Iran.
Ukrainian investigators had a good meeting Thursday with their Iranian counterparts, who proposed, among other things, that Iranian technicians would decrypt the information while the Ukrainians observed, Shevchenko said.
"Our thoughts are with the families & friends of the victims", he added.
On Friday, Ukraine's foreign minister said the United States has given President Volodymyr Zelensky important data about the crash, ahead of a call with Secretary of State Mike Pompeo.
The Transportation Safety Board of Canada said it was making arrangements to tour the site after an Iranian invitation.
Britain's Johnson yesterday called for a full, transparent investigation.
But unidentified officials told USA media that satellite, radar and electronic data indicated Tehran's air defence units downed the aircraft.