"I've been firm, I've been clear, but I don't think descending into insults is right for the way Canada engages with the world", the prime minister said.
Soon after the joint statement was announced, the USA president tweeted defiantly about not allowing "other countries to impose massive tariffs and trade barriers on its on farmers, workers and companies".
Trump, who argues his tariffs are meant to protect United States industry and workers from unfair global competition, told reporters he had suggested to the other G7 leaders that all trade barriers, including tariffs and subsidies, be eliminated.
Trump left the G7 summit in Canada early, then wrote on Twitter that Trudeau's remarks, including that his country would not be pushed around, "were very dishonest and weak". Eventually, Trump left earlier than expected and went to Singapore to meet with Kim Jong-un.
On Canada, he is repeating his criticism of Canadian dairy but says he wants to make a deal on NAFTA, with two different types of sunset clauses - a stumbling block for Canada in the past. Trump had at one point proposed that G-7 nations eliminate all tariffs, barriers and subsidies.
He said that other countries were imposing "massive tariffs" on the US.
That includes a $400-million investment from Canada as part of the overall three-year commitment, and also includes contributions from G7 partners and the World Bank.More news: Son of Ryan O’Neal, Farrah Fawcett charged with attempted murder
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Trudeau later said he reiterated to Trump that tariffs will harm industries and workers on both sides of the US-Canada border.
And he said he had told Trump "it would be with regret but it would be with absolute clarity and firmness that we move forward with retaliatory measures on July 1, applying equivalent tariffs to the ones that the Americans have unjustly applied to us".
In a statement, The Associated Press reported, a spokesman for Trudeau did not address Trump's tweeted insults.
But while the other leaders failed to persuade Trump that his view of global trade was overly simplistic and inaccurate, the US president surprised them during a meeting on Friday by suggesting that they work toward ending all tariffs and barriers, in what would effectively be the mother-of-all free trade agreements.
The statement made no reference to Russian Federation being invited back into the G7, but the leaders did say they would continue "to engage with Russian Federation on addressing regional crises and global challenges, where it is in our interests".
At the press conference Mr Trudeau insisted the US, Canada, Britain, France, Germany, Italy and Japan had figured out "consensus language" they could all agree to in the joint communique issued at the end of the G7 summit, despite the tensions with the US. "And we charge nothing", he said. "The president will continue to say what he says, on various occasions", said the prime minister.
Canada has given up slices of its dairy market in previous talks, including with the USA on the Trans-Pacific Partnership, a pact Trump quit.