Trudeau also said during a visit to Dublin that there were "clear disagreements" with the United States ahead of the G20 summit.
Trudeau also said during a visit to Dublin that there were "clear disagreements" with the United States ahead of the G20 summit this week, where US President Donald Trump is expected to attend.
"The choices made by the United States on trade and climate change are at odds with the majority of G20 countries, or even all the other G20 countries," he said after talks with Ireland's Leo Varadkar.
Trudeau predicted that there would be "robust and honest exchanges about how to serve not only our citizens but the whole planet" at the summit, while adding that such meetings were also a chance to try to find "common ground".
The United States and Canada are locked in a trade dispute, with the US accusing Canada of exporting its products at unfairly low "dumping" prices.
Canada is also a major supporter of the Paris Agreement to combat global warming, which Trump has said he wants to pull out of.
Both leaders issued thinly veiled criticism of their neighbours' politics.
"There are tremendous opportunities for countries like Canada and Ireland, at a time where perhaps our significant allies and trading partners in the case of both the US and the UK are turning inward or at least turning into a different direction," Trudeau said.
The sentiment was echoed by Varadkar, who reiterated his country's commitment to the European Union as it prepares for Britain's exit from the bloc.
"We each share a relationship with a very big neighbour, a neighbour that has to a certain extent decided to go in a different direction at least for the time being," he said.
Varadkar said that "unfortunately" Britain had chosen to leave the European Union and would not be able to negotiate free-trade agreements like the one between Canada and the EU until it has officially left.
"I can't see a scenario where Britain could remain a member of the EU, even in transitional period, and then negotiate other trade deals on their own".
Varadkar, the son of an Indian migrant and Ireland's first openly gay prime minister, said he and Trudeau had discussed a wide range of issues, including the benefits of immigration and diversity.
"Both countries and both governments are committed to multilateralism as the best means by which we can solve the world's problems," Varadkar said.