“This airplane was designed by clowns, who in turn are supervised by monkeys,” one of the fragments says.
US satellites registered a launch of two ground-to-air missiles shortly before an aircraft exploded in the air.
“We are in contact with our airline customer and stand by them in this difficult time,” it wrote on its Twitter page.
Earlier, the Ukrainian Embassy in Tehran ruled out an attack as a possible cause of the crash.
This was reported by the press service of the Iranian Ministry of Roads and Urban Development.