Trump had told Trudeau any retaliation would be a mistake and the prime minister agreed that it was "not something we want to do".
The joint communique was published online before Trump tweeted his disapproval after comments made by Canadian Prime Minister Justin Trudeau on the new trade tariffs. In that presser, he described the meeting as a "10" out of 10 and insisted he had very close personal relationships with, among others, Canadian Prime Minister Justin Trudeau, French President Emmanuel Macron and German Chancellor Angela Merkel.
Trudeau had announced that the G7 members - Canada, France, Germany, Italy, Japan, the United Kingdom and the USA - had agreed upon a joint communiqué, or formal statement, after a hard week on trade issues.
Kudlow said Kim must not see "American weakness" on the eve of the Tuesday summit.
This is what Larry Kudlow believes, that somehow Trudeau, by sticking up for his own country, has undermined the negotiations between Trump and Kim.
Justin Trudeau did a press conference. He said Canada has to stand up for itself.
"The loss of trade through tariffs undermines competition, reduces productivity, removes the incentive to innovate - and ultimately makes everyone poorer".
Mr Trudeau did not immediately respond, but his office said on Saturday after Mr Trump withdrew support for the communique that the Prime Minister had not said anything in his closing news conference he has not said to Mr Trump before.
North Atlantic Treaty Organisation is in crisis after US President Donald Trump questioned the future of the 69-year-old military alliance, attacking European countries for failing to pay their fair share towards the continent's defence.
Sunday, Trump's chief economic adviser Larry Kudlow accused Trudeau of undermining the USA and its allies with comments he made at the G7 summit.
The purely symbolic vote of solidarity came a day after White House trade adviser Peter Navarro said: "There is a special place in hell" for Trudeau for his "bad faith diplomacy" with Trump, as a dispute over trade escalated. That's what week, dishonest Justin Trudeau did. He had other things, bigger things on his plate in Singapore, he said. And what did Trudeau do as soon as the plane took off from Canadian airspace, Trudeau stuck our president in the back.
Trudeau: "The president will continue to say what he says at various occasions. That will not stand", he noted.
Before Trump even jetted to the conference on Friday morning, he floated the possibility of Russian Federation rejoining the G7. 'The United States has been taken advantage of for decades and decades, ' Trump told reporters, reiterating his long-standing view that Washington has been exploited for too long by existing trade arrangements.
"I mean we had Obama for the last eight years also threatening tariffs".
Canada's Foreign Minister Chrystia Freeland spoke against the United States over its tariffs on steel and aluminum on Friday during the Group of Seven (G7) summit in Charlevoix, Quebec.
'We have done just that at this summit, registering our deep disappointment at the unjustified decision by the USA to apply tariffs to European Union steel and aluminium imports'.
"I have made it very clear to the President that it is not something we relish doing, but it something that we absolutely will do", Mr. Trudeau said.
She also showed no signs of letting up-even if Trump retaliated by imposing tariffs on cars. Those countermeasures are set to take effect on July 1.