MacKay told a press conference at the Halifax International Security Forum that Russia — one of Syria's most important allies — should use its weight to end the conflict.
"We know in Syria there are countries like Russia that could be far more proactive, who could exert considerable influence and use their weight with the (Syrian President Bashar Assad) regime to end the violence," MacKay said just after giving his closing remarks at the three-day conference.
"If Russia truly wants to be embraced as a democratic, productive member of the world community, this is a time for them to show the right stuff."
Russia has backed Syria at the United Nations Security Council by repeatedly vetoing resolutions aimed at pressuring the Syrian government to end the war.
MacKay said Prime Minister Stephen Harper has recently met with Russian President Vladimir Putin, but did not go into the details of the discussion.
On Saturday, U.S. Sen. John McCain told the security conference that he was "ashamed" as an American over the U.S. non-action in Syria.
MacKay reiterated Sunday that Canada has no plans for a military intervention in Syria.
"I... believe that there is still further diplomatic paths we can pursue. I think a military intervention is always a last resort," said MacKay. "I think Syria is something we can't take our eyes off, in spite of what may be going on right now in Israel."
The ongoing threat of war in the Middle East was at the forefront of the conference in Halifax over the weekend, which drew about 300 delegates from more than 50 countries.
For the past several days, the Gaza Strip has been under fire by Israeli rockets. About 70 people have died, including civilians.
On Sunday, Palestinian medical officials said an Israeli missile flattened a two-storey house in a residential neighbourhood of Gaza City, killing at least 11 civilians, mostly women and children.
MacKay reaffirmed Sunday that Ottawa is standing behind Israel, saying that the country "has the right to defend itself."
"A country has a right to exist, and part of that existence means protecting your population, which is what Israel is desperately trying to do," said MacKay.
Canada and Israel have recently signed a non-binding memorandum of understanding covering defence and industrial initiatives, as well as information-sharing.
— With files from The Associated Press
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