"Very dishonest & weak", Trump said, adding that recently imposed United States tariffs on imports of Canadian steel and aluminium were in response to similar measures imposed on American dairy products by Canada.
Trudeau and Canadian Foreign Minister Chrystia Freeland later tweeted photos of the women's empowerment meeting, showing Trump's empty chair.
Trudeau said he told Trump directly that Canada 'particularly did not take lightly the fact that [the tariffs were] based on a national security reason'.
Earlier while still in Quebec, Trump said he wants to make a deal on NAFTA, and he's open to working with the current pact or striking separate agreements with Canada and Mexico - as long as they agree to renegotiate every five years. He says "we're not looking to play games".
Trudeau refused, and the meeting was off the table, but the lead ministers from both countries talked trade on the sidelines of the G7 leaders' talks on Friday.
Leaders of the G7 nations on Saturday papered over the cracks in their alliance at a summit in Canada but came away with little more than an agreement to disagree on trade, as Trump defiantly brandished his "America First" agenda.
China Views US Claims on South China Sea Militarization as Meddling
The previous week the US had withdrawn an invitation for Beijing to participate in the exercise known as Rim of the Pacific. Chinese foreign spokesperson responded to the USA accusation by saying the U.S.is like a robber playing a cop.
"We're like the piggy bank that everybody is robbing", he said at an earlier news conference as his counterparts continued their meeting in La Malbaie, Quebec, and officials hammered out a joint communique.
"No tariffs, no barriers, that's the way it should be, and no subsidies", Trump said on Saturday during a 30-minute press conference in La Malbaie. "Many of the current discussions about trade, especially with the U.S., despite the common commitment, will continue".
Donald Trump accused the summit's chairman Justin Trudeau of dishonesty. "The United States has been taken advantage of for decades and decades", Mr. Trump told reporters, adding that did not blame G7 leaders for the "unfair" trade deals.
Trump had come to Quebec insisting on his long-standing claim that America has been exploited for too long by existing trade arrangements - and he was met by counterparts equally determined to protect the "rules-based" worldwide system.
Such a move could make it almost impossible to renegotiate the terms of the 1994 NAFTA pact between the United States, Canada and Mexico.
House Minority Leader Nancy PelosiNancy Patricia D'Alesandro PelosiOvernight Health Care - Sponsored by PCMA - DOJ move against ObamaCare sets off frenzy Overnight Health Care - Sponsored by PCMA - New White House ad campaign targets opioid addiction Pelosi: "Medicare for All" should be "evaluated" if Dems win House MORE (D-Calif.) chided Trump and his Commerce Department. The United States pays enormous tariffs on dairy.
And she urged against what she described as "tit-for-tat" escalation of a potential trade war between the U.S. and European Union, before calling for a continued "constructive dialogue". Canada and Mexico are also taking action in retaliation.