Mr. Trump's tweets followed a press conference by Canadian Prime Minister Justin Trudeau, who said that Canada would be going through with retaliatory tariffs given the U.S.'s insistence on steel and aluminum imports.
Macron and Trudeau had criticized Trump's tariffs on imports of aluminum and steel into the country, with Macron suggesting that the US could be excluded from a joint statement.
Although Trump says his tariffs are necessary to protect U.S. industry and workers, Canada and the European Union have denounced them as illegal.
On the ultimate goal for global trade rules: "You want a tariff-free, you want no barriers, and you want no subsidies, because you have some cases where countries are subsidizing industries, and that's not fair".
Trump had already roiled G-7 members ahead of the summit and raised fears of a trade war when he placed tariffs on steel and aluminum from Canada, the European Union and Mexico.
In a freewheeling news conference at the G7 summit in La Malbaie, Trump defended his contentious case for bringing Russian Federation back to an expanded G8, and he riffed again on what he said are unfair trade deficits with his country.
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Nyantakyi will not be able to vote next week to determine whether Morocco will be able to host the next World Cup. This is by no means an admission of wrong doing for issues on the video" he said.
"The United States has been taken advantage of for decades and decades", Trump said.
It's a startling attack on the leader of the US neighbor and ally.
I think it is going to be very positive.
"Our values and interests are built through multilateralism, including American interests", Macron said in a tweet.
At issue are US tariffs against Canada and Trudeau's effort to retaliate against its neighbor - as well as Trudeau's comment to reporters that all seven leaders had come together to sign a joint declaration after the G-7 meeting.
Trump will travel directly to Singapore from Canada to attend the meeting.
With Macron, on the back of a cozy meeting at the White House last month, Trump said they had a "good relationship" although he admitted they were having some issues on trade. "The President of the United States thinks that the U.S. has been treated in an unfair way by Europe and by others, and the others think that this is not the case", European Commission President Jean-Claude Juncker told a press conference in La Malbaie.
While Trump's relationship with some of the G7 members has reportedly been tense, one quickly came to his defense.