Trudeau picked up promises of investments and jobs during his first official visit to San Francisco. Among them: Salesforce CEO Marc Benioff announced the online business software company will invest another $2 billion in its Canadian operations.
He was scheduled to appear on Saturday in Los Angeles, with Mayor Eric Garcetti.
Trump called the 24-year-old agreement a job-killing "disaster" on the campaign trail, and he has threatened to pull out unless the deal requires more auto production in the U.S., while shifting additional government contracts to U.S. companies.
Trudeau argued that the deal has sent benefits both ways across the border.
He said 9 million jobs in America are tied to trade and investment with Canada and "the truth is that both Canada and the United States are winning. And so is Mexico. And that's exactly how we should keep it."
But he added: "President Trump and I agree about this: Too many people have been left behind, even as our economies surged."
But an agreement, he warned, will take "a willingness to compromise on all sides."
The location of the speech carried symbolic weight, alluding to the longstanding trade relationship between the U.S. and Canada. In 1988, Reagan and then-Prime Minister Brian Mulroney signed the first free trade agreement — a precursor to NAFTA.
In his speech, Trudeau made repeated references to the historic connections between the two countries and argued that backing away from NAFTA could unspool deep ties across the continent — with an unknown cost.
The liberal Trudeau argued that differing political views need not stand in the way of trade agreement, alluding to the Republican president.
Reaching agreements has always required "persistence and no shortage of sunny, Reagan-esque optimism on both sides," he said.
Uncertainty over Trump's immigration policies has provided momentum for Trudeau's economic pitch to Silicon Valley, where many companies that rely on foreign workers have become uneasy.
On his visit to Northern California, Trudeau promoted his country's fast-track employment permit for certain workers, dubbed the "global skills strategy visa."
Trudeau also met Thursday with Amazon Chief Executive Jeff Bezos as Bezos considers possible locations for a second headquarters. Toronto, which has created a government-sponsored innovation hub for tech companies, was the only one of several Canadian cities that made the shortlist.
Trudeau's stop in San Francisco highlighted the already strong ties between Canada and California, particularly in research, academia and technology.
The separate meetings Friday with Gov. Jerry Brown and Lt. Gov. Gavin Newsom were closed to the media.
In brief remarks to reporters before meeting with Newsom, Trudeau said it was good to talk about all the issues that bind California and Canada.
Newsom thanked Trudeau for his energetic leadership on the international stage at a time of political uncertainty, an apparent reference to U.S. President Donald Trump.
Trudeau spent Thursday pitching tech companies on investing in Canada while touting the country's fast-track visa for highly skilled workers.