"I think it will be very positive", Trump said, without giving details.
Canadian Foreign Minister Chrystia Freeland said her country "will not change its mind when it comes to the illegal" application of tariffs.
"We have massive trade deficits with nearly every country".
He's also threatened to tear up the NAFTA agreement with Canada and Mexico.
The proposal was supported by other leaders present, the official said.
The two-day summit in Canada has been marred by fears of a trade war and tit-for-tat exchanges of hostile tweets, with U.S. trading partners furious over Mr Trump's decision to impose tariffs on steel and aluminium imports from the EU, Canada and Mexico as part of his "America First" agenda. "We'll see how it all works out, but we've made a lot of progress", Trump said, sitting by Trudeau after talks that an official said were marked by "strong disagreement" but "not heated".
The French presidency says Macron told Trump during a call last week that new USA tariffs on European, Mexican and Canadian goods are illegal and a "mistake". G7 chiefs have largely praised Trump for his efforts to stabilize the Korean peninsula, but they are unhappy he pulled out of an global agreement to limit Iran's nuclear ambitions.
Mr Trump plans to leave the summit mid-morning on Saturday, four hours earlier than originally planned, to fly to Singapore ahead of his historic meeting with North Korean leader Kim Jong-un.
He made the comment at the White House yesterday after hours of further escalating his rhetoric against long-time allies over United States trade practices.
The president called for the G-7 to readmit Russian Federation, to the shock of the other foreign leaders, who, in concert with then-President Barack Obama had kicked the country out of the club as a rebuke to Moscow for illegally annexing Crimea.
French President Emmanuel Macron turned on President Trump Thursday, slamming the American leader over potential trade tariffs and his position on climate change; warning Trump the G7 could quickly become the G6. Both Moscow and Trump have denied the allegations.
Trump has pointed to Canadian Prime Minister Justin Trudeau's criticism of him as a reason for withdrawing from the consensus statement.
"You know, whether you like it or not, and it may not be politically correct, but we have a world to run and the G7, which used to be the G8, they threw Russia out, they can let Russia come back in, because we should have Russia at the negotiating table", Trump told reporters before leaving Washington.