Trudeau also said the U.S. electoral system and its institutions had held up in the aftermath of last week's violent attack by "a small, angry mob" on Capitol Hill.
"There is a need for a re-engaged United States in global circles," said Trudeau.
"One of the things that a lot of the traditional allies and friends of the United States are looking forward to is a re-engagement on some of the big themes, whether it's freer trade, whether it's climate change, whether it's protecting democracy."
Outgoing President Donald Trump often clashed with traditional allies on trade. He imposed tariffs on Canadian aluminum and steel and paralyzed the World Trade Organization's role as global arbiter on trade by blocking appointments to its appeals panel.
On climate, Trump withdrew from the Paris Agreement that set up a global framework to reduce carbon emissions, and he seemed more at ease with leaders like Russian President Vladimir Putin than with NATO allies, who he berated for not spending enough on their armed forces.
"We're seeing a world that is changing rapidly. The rise of a much more assertive and sometimes problematic China, the shifts in poles of power around the world, the rise and strengthening of Asia as an economic focal point. These are things that are needing to be responded to," he said.