In an interview taped on Thursday, which aired Sunday night, Trudeau said that Russia was upset about its men's Olympic hockey team losing out on a shot at a medal in Sochi.
Trudeau was answering a question about whether Canada should do more to help Ukraine, where violence had hit its worst point since the Soviet era, with 75 people were killed in two days. The EU and Canada announced economic sanctions against President Viktor Yanukovych that day.
"Canada should do more," Trudeau said in the interview on Radio-Canada's Tout le monde en parle, a French-language interview show that's enormously popular in Quebec.
The Liberals had been urging the government to do more, Trudeau went on to say in French.
"President Yanukovych has been made illegitimate. It's very worrying, especially because Russia lost in hockey, they'll be in a bad mood. We fear Russia's involvement in Ukraine," Trudeau said.
"Just because of hockey?" asked Guy Lepage, the show's host.
"No. That's trying to bring a light view in a situation that's extremely serious," Trudeau said.
Another guest, singer and actor Dan Bigras, then pointed out they were talking about massacres, something Trudeau agreed was horrible.
Conservative MPs took aim at Trudeau Monday on Twitter, including Employment Minister Jason Kenney and Industry Minister James Moore.
"So Justin Trudeau, whose favourite regime is 'the basic dictatorship of China,' thinks the deadly crisis in Ukraine is a laughing matter," Kenney said on Twitter, referring to Trudeau citing China as the country he most admired other than Canada.
Moore simply tweeted the quote and the word "Unreal."