U.S. President Joe Biden on Thursday said he hoped president-elect Donald Trump would rethink his plan to impose tariffs on Mexico and Canada, saying it could "screw up" relationships with close allies.

"I hope he rethinks it. I think it's a counterproductive thing to do," he told reporters in Nantucket.

"We have a unusual situation in America. We're surrounded by the Pacific Ocean, the Atlantic Ocean, and two allies: Mexico and Canada. The last thing we need to do is begin to screw up those relationships."

Trump on Monday said he would impose tariffs on Canada and Mexico when he takes office in January until they clamped down on drugs and migrants crossing the border, a move that would appear to violate the U.S.-Mexico-Canada free-trade deal.

Such a move would throttle the Canadian economy. 

WATCH | What Trump's threat means for Canada:

Everything you need to know about Trump’s tariff threat

With U.S. president-elect Donald Trump threatening to slap a 25 per cent tariff on all goods from Canada, The National’s Adrienne Arsenault asks CBC’s Peter Armstrong and Alex Panetta to break down what it could mean for the economy and what Canada’s options are to respond.

Trudeau, Sheinbaum speak to Trump

In a phone call after Trump's post, Prime Minister Justin Trudeau listed things Canada has already done to improve the situation at the border and suggested Canada's situation wasn't as dire as Mexico's.

Trudeau said his conversation with the president-elect as a "good call" during which he laid out the "facts."

Mexico's President Claudia Sheinbaum said on Thursday she did not specifically discuss tariffs in a call she held with Trump on Wednesday.

Following the call on Wednesday, Trump said Sheinbaum had "agreed to stop migration through Mexico, and into the United States, effectively closing our Southern Border."

Sheinbaum, however, said she had laid out a strategy that "attended to" migrants before they reached the U.S. border. "Mexico's stance is not to close borders, but to build bridges between governments and their peoples," she said in a post on X after Trump's post.