The U.S. Treasury chief said he has relayed some of the G7 comments to Trump and added that the U.S. president would address trade issues with other G7 leaders, but declined to speculate on any outcomes.
Trudeau last week slammed the Trump administration's decision, calling the tariffs an "affront" to the historic alliance between the two nations.
Japanese Finance Minister Taro Aso said it was "unprecedented" for the group to stand united against USA policy, while Bank of Japan Governor Haruhiko Kuroda said the effects of protectionist policies on the global economy "warrant attention".
Le Maire said it's now up to the U.S.to take action to rebuild confidence among G7 members - and to avoid any escalation next week during the G7 leaders' summit.
French Finance Minister Bruno Le Maire also said Mnuchin was alone on the tariff issue, with the group becoming a "G6 plus one" as the six expressed "total incomprehension" over the United States move.
Speaking after the meeting, Le Maire said the European Union was poised to take counter-measures against the US.
Speaking on NBC's Sunday morning news show Meet the Press, Trudeau says he wants to make sure Americans, and more specifically Trump supporters, hear the message that they are going to feel financial strain and pain from the steel tariffs Trump imposed on Canada last week.
France's Bruno Le Maire, the finance and economy minister, was more blunt in his assessment of the Whistler meetings, where ministers confronted Mnuchin.
In a statement issued by Canada, the G7 finance officials agreed that "decisive action is needed" on the tariff issue at a summit of G7 leaders next week in Charlevoix, Quebec.
Last week, the U.S. confirmed it would be imposing a 25% tariff on steel imports from the EU, Canada and Mexico and a 10% tariff on aluminium.
Mnuchin denied that the meeting had devolved into a "G-6 plus one", but his counterparts underscored the strong pushback against the Trump administration's protectionist stance.
US?President Donald Trump on Thursday made good on a threat to impose permanent tariffs of 25% on steel imports and 10% on aluminium imports from the EU, Mexico and Canada, ending temporary exemptions they had been granted. "But this is a very rare case where opposition against the United States was unanimous", Aso told reporters. "The ball is now clearly in the camp of the United States".
A few hours later, Trump took to Twitter again, suggesting that the USA has been taken advantage of by it allies.
"We see that response as being a way to get us back to the table so the impacts actually don't happen", Mr Morneau said.
The complaints came on the eve of a visit by Ross to China to try to secure long-term purchases of USA farm and energy commodities to help shrink the United States trade deficit and avert a looming tariff war between the world's two largest economies.