Speaking at an worldwide conference on global challenges in New Delhi Tuesday, Harper said he does not believe Iran would have shot down a civilian aircraft deliberately - but the fact that Tehran knew it could happen and still allowed normal civilian air traffic "tells you something about the nature of that regime and its priorities".
Zelensky and Trudeau also discussed "further co-ordination of efforts to ensure proper worldwide legal liability of those responsible for the plane crash", according to a more detailed Ukrainian government account of their call - their third in a week.
After his speech, Iran's judiciary said it had arrested some people for their role in shooting down the plane, judiciary spokesman Gholam Hossein Esmaili said on Tuesday.
Also Tuesday, Iran's judiciary said that 30 people had been detained in the protests, and that some were released, without elaborating further. "This is not a normal case and the whole world will follow the case in our court".More news: Mitch McConnell welcomes end to Nancy Pelosi's 'one-woman blockade' on impeachment
Iranian Supreme Leader Ayatollah Ali Khamenei expressed his "deep sympathy" to the families of the 176 victims on January 12 and called on the armed forces to "pursue probable shortcomings and guilt in the painful incident".
176 people were killed after Iran mistakenly shot down a passenger plane.
The plane, en route to the Ukrainian capital of Kyiv, was carrying 167 passengers and nine crew members from several countries, including 82 Iranians, 57 Canadians - including many Iranians with dual citizenship - and 11 Ukrainians, according to officials.
But 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. But the country came clean by the weekend, acknowledging "human error" caused the downing of the plane, which the government said was mistaken for a threat.
Tehran has faced an escalating confrontation with the West and a wave of unrest since the United States killed Iran's most powerful military commander in a drone strike on January 3.More news: United States 'outraged' by latest attack on Iraqi base
Longstanding US-Iran tensions have soared since Jan 3 when missiles fired from a US drone killed a top Iranian commander, Qasem Soleimani, near Baghdad's airport.
He added that the global community has been "very, very clear about needing to have a non-nuclear Iran" but also in "managing the tensions in the region that are brought about by U.S. actions as well".
Iran's military had been on high alert following increased tensions between Tehran and Washington.
Iranian officials at first fiercely denied that Iran was to blame, provoking outrage and protests in Iran once they accepted culpability. As other countries began to declare their belief that an Iranian missile had brought down the airliner, Tehran's denial persisted.More news: 6 questions ahead of the final Democratic debate before voting begins