Other G7 leaders, including host Canadian Prime Minister Justin Trudeau, have been critical of Trump's trade policy ahead of the summit, condemning his administration's imposition of tariffs on steel and aluminum imported from allies including Canada and the European Union.
He added that EU Commission President Jean-Claude Juncker thanked Trudeau "for the excellent preparation and chairing of this challenging summit".
"They should let Russian Federation come back in because we should have Russian Federation at the negotiating table".
"We are like the piggy bank that everybody is robbing", he said.
The U.S. president is lashing out on several fronts.
On the eve of Mr. Trump's meeting with Mr. Kim, one of the president's top trade advisers, Peter Navarro, said there was "a special place in hell" for leaders like Mr. Trudeau, accusing him of engaging in "bad-faith diplomacy" with Mr. Trump. Or we'll stop trading with them.
The president refused to sign a solidarity agreement with the other G7 members and suggested more tariffs could be in the works. He added, "Canadians, we're polite, we're reasonable, but we also will not be pushed around".
Trudeau has so far not commented on Trump's tirade.
The relationship between the US and its allies was already off-balance after Mr. Trump just a week before the summit imposed 25% tariffs on steel and 10% tariffs on aluminum from the European Union and Canada.
He will arrive at the annual gathering, held this year in Quebec, but will leave on Saturday morning before the event is over, heading to Singapore for his highly anticipated summit with North Korean leader Kim Jong Un. "We joined the communique in good faith", Kudlow said.
June 10 - Trump's economic advisor Larry Kudlow tells CNN that Trudeau "stabbed us in the back".
"I've never seen language like this, least of all from subordinates of the president directed at the prime minister of their greatest friend and ally", Mulroney said.
"Justin Trudeau's left eyebrow detached after meeting Trump - so what?"
"That's unconscionable", Heyman said."Anybody who represents the United States of America from the White House using that kind of language with any world leader of any type, I think is uncalled for".
The now-rejected communique acknowledged the importance of "free, fair and mutually beneficial trade and investment". "Well, the in-factual, the non-factual part of this was they have enormous tariffs", Kudlow said.