Trump is set to hold the first meeting between a sitting USA president and North Korean leader on June 12.
Trump, who repeated that his tariffs are meant to protect USA industry and workers from unfair worldwide competition, said he had suggested to the other G7 leaders that all trade barriers, including tariffs and subsidies, be eliminated.
Trudeau said he had reiterated to Trump that tariffs would harm industries and workers on both sides of the US-Canada border.
The U.S. president left before the end of the summit and will fly to Singapore for a meeting with North Korean leader Kim Jong Un, which he described as a "mission of peace".
Mr Trump was heading into a bigger controversy over trade as other G7 leaders, including host Canadian Prime Minister Justin Trudeau, have been angered over Washington's imposition of tariffs on steel and aluminium imported from allies including Canada and the European Union.
The summit came during an ongoing trade dispute with China and served as a precursor to the unprecedented meeting with Kim, in which Trump has sought to extend a hand to the Asian autocrat who has long bedeviled the worldwide order.
Trump will leave the gathering at 10:30 a.m. on Saturday and put Everett Eissenstat, his deputy assistant for global economic affairs, in charge for the remaining sessions, White House spokeswoman Sarah Sanders said in a statement on Thursday. Bannon said China is "now on notice that Trump will not back down from even allies" complaints in his goal of "America First'".
Speaking today 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.
He said USA farmers had been harmed by tariffs and other barriers and warned that US trading partners would need to provide him with more favorable terms.
World leaders from the group of the seven richest nations are set for a dramatic showdown with the firebrand Republican as they pressure him to lift levies on steel and aluminium.
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The couple also rode in a horse drawn carriage during the parade featuring more than 1,400 soldiers, 200 horses and 400 musicians. While Queen Elizabeth concentrates on affairs of state, Prince Philip is in charge of matters such as running the royal estates.
Trump cited progress on reaching an agreement on the North American Free Trade Agreement with Canada and Mexico, saying the final outcome would lead either to an improved trade deal or separate pacts with the two USA neighbors. When asked for a response to Trump's remarks, a senior Canadian official said that the nations can manage their differences through discussions.
Trump and other world leaders don't agree on a wide range of issues from trade to the environment as well as Iran and the construction of a new USA embassy in Jerusalem.
Discussing Russia's absence, Trump made the vague comment that "something happened a while ago where Russia is no longer in".
Trump's early departure means he will miss a working session among the leaders on climate change and clean energy, as well as talks among the G7 and poorer countries focused on the health of oceans.
Trump bragged at a fundraising speech later that month that he made up facts in a meeting with Trudeau, claiming the us runs a trade deficit with its biggest ally.
Trump tweeted Thursday evening that he wants to remind Trudeau - and French President Emmanuel Macron - that Canada and France have been charging the U.S.
Abe is not the only world leader to have tried charming Trump and failed to come away with concessions from the U.S. leader.
Russian Federation was expelled from what was then called the G8 in 2014 because of its annexation of Crimea from Ukraine.
"We Europeans and the Japanese are not ready to give up everything to get" Trump's signature, he said, adding that would be a "mistake".