"His tariffs are too high and he doesn't seem to want to move, and I told him forget about it", Trump said.
"We don't like their representative very much", Trump said in an apparent reference to Canada's Minister of Foreign Affairs Chrystia Freeland, who has been negotiating with U.S. Trade Representative Robert Lighthizer.
The two nations have been locked in negotiations for a year on a rewrite of the 25-year-old continental trade deal that Mr Trump blames for losses of USA jobs and industry. "That's the mother lode, that's the big one".
But Mr Lighthizer on Tuesday said time was running out for Canada to be included, and Mexico's trade negotiator Kenneth Smith Ramos said the two countries are ready to proceed.
At the end of his statement, Trump said that he loves Canada and he has "so many friends" from the country.
"The fact is, Canada is not making concessions in areas where we think they're essential", he said at the Concordia Summit in NY.
Trump and several of his top aides have said Canadians were refusing to rework NAFTA because they want to continue protecting their local dairy industry through a controversial management program. He declined to answer when asked whether Trump had lied.
Trump questions Kavanaugh's accuser, says opponents want to 'destroy' nominee
Trump and other Republicans, cautious of alienating women, have treated Ford carefully while calling for a quick vote. Asked if he would ask the FBI to open a deeper investigation, Trump said he was content to "let the senators do it".
Trump has demanded major changes to NAFTA, which he has said caused US manufacturing jobs to move to low-wage Mexico.
The prospects for a quick deal to update the North American Free Trade Agreement appeared to dim on Wednesday after Trump blasted Canada's stance and threatened to impose tariffs on cars imported from Canada.
"The Americans are finding that the negotiations are tough because Canadians are tough negotiators, as we should be", the prime minister told reporters in Ottawa. "Very bad for us", Mr Trump said.
Disputes have also arisen between over President Trump's request for increased access to Canada's protected dairy market. The U.S. president stayed seated as he extended his hand for a cursory handshake. Officials in the PMO insisted no such request had been made, given already close contact with the White House.
Earlier Wednesday, Canada's USA envoy David MacNaughton, who has taken part in the Washington talks alongside Foreign Affairs Minister Chrystia Freeland, pegged the likelihood of a new trade deal by Sunday's congressional deadline at a "five" on a scale of one to 10. Another sticking point is Canada's protected dairy industry, which isn't in the current deal but where the USA wants concessions.
"We'll see where it goes, but so far it's been tough", he said.