The two men were identified as 19-year-old Pouri Nour Mohammadi and 30-year-old Delavar Suyed Mohammad Reza.
The images, released by the international police agency at Lyon in France, showed both the Iranian men boarding the plane at the same time.
They arrived in Kuala Lumpur using their Iranian passports on February 28 and left on Saturday on board MH370 to Beijing on stolen passports, Interpol Secretary General Ronald K Noble said.
One used an Italian passport while the other had an Austrian passport both stolen in Thailand last year.
"Inclined to believe that we are moving towards a human smuggling issue and not necessarily #terrorism. #MH370," Interpol's Twitter handle @INTERPOL_HQ quoted Noble as saying.
The Beijing-bound Boeing 777-200 plane with 227 passengers on board, including five Indians and one Indian-origin Canadian and 12 crew members, vanished from radar screens after taking off on Saturday.
Earlier in the day, Malaysia's Inspector-General of Police Tan Sri Khalid Abu Bakar said they believe Mohammadi's intended destination was Frankfurt in Germany.
"So far, we believe he is not likely to be a terrorist," Bakar said. Mohammadi used the passport of Austrian Christian Kozel who had reported it missing in Phuket, Thailand.