"I guess they're going to go back to the drawing board and check it out, right?" he said, warning that if his fellow leaders make good on threats to take retaliatory measures, they could find themselves shut out of American markets.
Mr Trump's presidency has been clouded by a federal investigation into alleged Russian meddling in the 2016 presidential election, and possible collusion by his campaign.
When Trump was pressed about the annexation of Crimea, he placed the blame on President Barack Obama for failing to handle the situation.
Russian Federation was expelled from the group four years ago as a outcome to its annexation of Ukraine's Crimea region.
In his final G7 news conference, Mr Trump described his trip to Singapore as "a mission for peace" that he was "confident" about.
"For us, it was important to have a commitment to rules-based trade", Germany's Chancellor Angela Merkel said. "Whether you like it or not, and it may not be politically correct, but we have a world to run".
Lava flow from Hawaii volcano engulfs neighborhood, creates new land
Geological Survey. "Rainfall really makes a difference", Hawaii Volcanoes National Park spokeswoman Jessica Ferracane said. The lava from Kilauea volcano that flowed into Kapoho Bay has created almost a mile of new land, the officials added.
Speaking on Saturday during a rare news conference, Trump said he pressed for the G-7 countries to eliminate all tariffs, trade barriers and subsidies in their trading practices.
"What worries me most however is the fact that the rules-based global order is being challenged, quite surprisingly not by the usual suspects but by its main architect and guarantor: the USA", he said.
Trump created a distraction when he walked in late for Saturday's breakfast meeting during the Group of Seven summit of leading industrialized nations being held in Quebec.
Trudeau said the communique has "strong commitments about the actions we are going to take".
Zionist Troops Kill Palestinian Youth in West Bank Village Raid
Israel says many protest participants were Hamas members and militants trying to breach the border and launch attacks. This year, the protests take on added significance after the U.S. recognition of Jerusalem as Israel's capital.
"We are ready for this", he said.
Despite his sharp differences with US allies, the president insisted he has a "great relationship" with his foreign counterparts. A Canadian official said the leaders discussed accelerating the pace of the talks.
Trump is telling reporters that he told world leaders that the USA will take whatever steps necessary to prevent unfair foreign trade practices.
For example, on Friday evening, the White House issued a statement saying Trump and Canadian Prime Minister Justin Trudeau were very close to a deal to rework the North American Free Trade Agreement.
The president has angered Canada, Mexico and European countries with his recent decision to impose tariffs on steel and aluminum imports. He says gender equality must "cut through" everything the G-7 does.
President Trump concluded his visit to the Group of Seven summit on Saturdaywith warnings to USA allies, saying if they don't eliminate barriers to trade, they could lose access to the us economy.
A Tank Gets in a Chase with Police
The Virginia Army National Guard is expected to release information late Wednesday about his military status. Police chase solider who stole a military vehicle in Virginia for almost two hours until the man surrendered.
Trump contends that other countries "have been taking advantage of the United States on trade".