He then issued an ultimatum: "Why isn't the European Union and Canada informing the public that for years they have used massive Trade Tariffs and non-monetary Trade Barriers against the U.S. Totally unfair to our farmers, workers & companies".
Following the G7 summit in Canada's Quebec, Trump is en route to Singapore where he will meet with North Korean leader Kim Jong-un.
The move was in response to the USA tariffs, which include a 25 per cent tax on steel and a 10 per cent tax on aluminum imports from Canada and many other allied countries.
Canadian Prime Minister Justin Trudeau on Saturday rejected a USA demand for a sunset clause in NAFTA but said he was prepared to compromise on the issue, which is holding up talks to update the 1990s-era pact.
However, Canadian PM's office responded to the "tweeting attack" in a statement saying that Justin Trudeau did nothing to provoke the backlash from Donald Trump.
The outburst against Trudeau, and by association the other members of the G7 group, is only the latest incident in which Trump has clashed with America's closest allies.
The President warned Canada and Europe to back off their threats to hit back with retaliatory trade measures on July 1 if the US does not lift the steel and aluminum levies. The G-7, in its current form, consists of the United States, Canada, Britain, Germany, France, Italy and Japan.
One source speaking on the condition of anonymity described the overall cordial tone with Trump as an attempt to lay a positive foundation for tougher discussions that would follow.
"He really kind of stabbed us in the back", Kudlow said. Furthermore, they agreed on the importance of bringing negotiations on the North American Free Trade Agreement (NAFTA) to a successful and timely conclusion.
"I think it would be an asset to have Russian Federation back in, I think it would be good for the world, I think it would be good for Russian Federation, I think it would be good for the United States, I think it would be good for all the countries of the current G7", he said. He says that we are the problem with tariffs.
She acknowledged that Canada and the US have disagreed on significant issues in the past - such as the Vietnam and Iraq wars - and still have differences today when it comes to things like climate change and the steel and aluminum tariffs.
But in brief remarks to reporters before their bilateral meeting Friday afternoon, Trump seemed to lighten the mood, cracking a joke about Canada dropping all tariffs and claiming that relations between the two countries were perhaps better than they had ever been. Like Trudeau, Trump has sparred publicly with Macron on Twitter over what the USA president calls unfair trade deals that impoverish American interests to the benefit of its allies. "Americans stand with you, even if our president doesn't".
On his way to Singapore Saturday, Mr. Trump tweeted that he thinks fair and reciprocal trade will happen. "And no subsidies. I even said, 'no tariffs!'" Trump insisted.
That leaves Trump diametrically opposed with Canada, which says renegotiating the deal every five years would create perpetual uncertainty and harm long-term investment.
It was a "a long litany of recriminations, somewhat bitter reports that the United States was treated unfairly", said the French official, who spoke on condition of anonymity.