Updated at 10:25 p.m. ET
Leaving the Group of Seven Summit for Singapore, President Trump tweeted that he has instructed U.S. representatives to not endorse a joint communique issued by the G-7 leaders.
The president tweeted "Based on Justin's false statements at his news conference, and the fact that Canada is charging massive Tariffs to our U.S. farmers, workers and companies, I have instructed our U.S. Reps not to endorse the Communique as we look at Tariffs on automobiles flooding the U.S. Market!"
Trump said his statement was in response to Canadian Prime Minister Justin Trudeau's comment following the summit that Canada "would not be pushed around."
"PM Justin Trudeau of Canada acted so meek and mild during our @G7 meetings only to give a news conference after I left saying that 'US Tariffs were kind of insulting' ... Very dishonest & weak," the president tweeted.
Trump posted his comments from Air Force One as Canada was releasing the official communique that had been endorsed by all seven leaders.
It said that the United States, Canada, Britain, France, Italy, Germany and Japan had agreed on the need for "free, fair, and mutually beneficial trade."
Trudeau's office responded to Trump's tweet saying "We are focused on everything we accomplished here at the #G7 summit. The Prime Minister said nothing he hasn't said before — both in public, and in private conversations with the President."
Earlier on Saturday, President Trump concluded his visit to the Group of Seven summit with warnings to U.S. allies, saying if they don't eliminate barriers to trade, they could lose access to the U.S. economy.
Speaking in a solo press conference from the resort town of La Malbaie in Quebec, the president said that for too long, U.S. trade has suffered from "bad" trade deals agreed to by past U.S. presidents.
"The United States has been taken advantage of for decades and decades," Trump said. "I don't blame other leaders for that, I blame our past leaders. There was no reason that this should have happened."
Trump said he pushed for the elimination of trade barriers, including subsidies and tariffs, at the G-7 meeting.
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. All three trading partners have threatened to retaliate with their own levies against U.S. imports.
"If they retaliate, they're making a mistake," Trump said.
While talking tough with U.S. allies such as Canada and the EU, Trump repeated his call for Russia to be allowed back into the elite club, which includes Britain, Canada, France, Germany, Italy, the U.S. and Japan. Russia joined the G-7 in the 1990s, making it the Group of Eight, but was expelled after its annexation of Crimea in 2014.
"They should let Russia come back in, because we should have Russia at the negotiating table," Trump said. Readmitting Russia to the group would be an "asset," according to the president.
He left the summit four hours earlier than originally planned and will miss key talks on the environment, including working sessions on climate change, clean energy and the health of the oceans. Trump is heading to Singapore, where he is scheduled to meet on Tuesday with North Korean leader Kim Jong Un.
Trump called the summit a "one time shot" for Kim, but expressed optimism at the beginning of talks with the North Korean regime. "I think within the first minute I'll know," Trump said. "Just my touch, my feel. That's what I do."
The U.S. wants North Korea to give up its nuclear weapons program, a demand North Korea has rejected without concessions from the U.S.
Trump has previously threatened North Korea with military action if it "acts unwisely." Roughly 28,000 American service members and civilian military personnel are currently stationed in South Korea.
"This is unknown territory in the truest sense. But I feel really confident," Trump said of Monday's meeting, which is the first between a North Korean leader and sitting U.S. president, "It's never been done, It's never been tested. So we are going in with a really positive spirit."