"We have a great relationship" with the leaders of nations like Canada.
"If we're unable to make a deal we'll terminate Nafta", Trump said Friday morning.
"With one country we have $375 billion in trade deficits". Canada has been adamant it won't agree to such a clause.
But Trump said that the notion that the G7 summit was in any way contentious was "fake news", telling reporters Saturday that the conference had been "so wonderful".
Trudeau refused, and the meeting was off.
Trump, who last week slapped tariffs on steel and aluminum imports from Canada, the European Union and Mexico, left the Group of Seven summit early but not before threatening to cut off trade with countries that treated the United States unfairly. "We can't lose it", he said.
"You know, whether you like it or not, and it may not be politically correct, but we have a world to run".
Trump, who angered Washington's top allies last week when he imposed tariffs on steel and aluminum imports from Canada, the European Union and Mexico, issued a broad indictment of global trade, with swipes at the G7 and India.
Trump's tariffs initially went into effect in March, aimed specifically at China, but the White House announced in May that the three allies would no longer be exempt from the taxes. He says: "That's the way it should be".More news: 5 talking points ahead of the men's French Open final
"We're either going to have NAFTA in a better negotiated form or we're going to have two deals", the USA president said.
"I think it would be good to have Russian Federation back in", Trump said during the conference.
Though the USA appears increasingly isolated from its allies, Trump on Saturday insisted that his relationships with other leaders remains "great". The United States' closest trading partners - the EU, Canada and Mexico - have vowed to impose retaliatory tariffs on scores of USA products beginning in the coming weeks.
Speaking about Russia's military incursion in Crimea, a peninsula that was part of Ukraine, Trump on Saturday blamed President Obama for the annexation.
Trump says he will depart shortly for Singapore on a "mission of peace".
The U.S. president is lashing out on several fronts. Commerce Secretary Wilbur Ross said the tariffs on the former two countries were due to a lack of progress in NAFTA talks. Canadian officials explained that the United States and Japan did not sign on because they did not want to commit to firm targets to reduce plastics.
Leaders of the Group of Seven industrialized nations agreed at the conclusion of their summit on Saturday on the need for "free, fair, and mutually beneficial trade" and the importance of fighting protectionism, their communique said.
The summit host, Canadian Prime Minister Justin Trudeau, kicked things off without waiting for those he described as "stragglers" to arrive.
Trudeau had made the issue of gender equality a priority for the gathering.