In that black-and-white photo, posted by US Press Secretary Sarah Sanders, Mr Trump appears to talk confidently as other leaders listen.
"He is not going to permit any show of weakness on the trip to negotiate with North Korea -" Kudlow added.
And Roland Paris, a former foreign policy adviser to Trudeau, jabbed on Trump on Twitter: "Big tough guy once he's back on his airplane".
Despite the tensions at the gathering in Canada, Mr Trump rated his relationship with their leaders as a "10" - naming Germany's Angela Merkel, French president Emmanuel Macron and Canada's Justin Trudeau, but not the UK's Prime Minister.
However, former US ambassador to Canada Jim Blanchard said the auto sector in the USA won't tolerate this threat of more trade action, saying that both that industry and American farmers want to see a renewed trade relationship with Canada.
"We have to keep a cool head now and draw the right conclusions", Maas said.
Trump was miffed by comments Trudeau made Saturday during a news conference. But Trump had already said he would not hesitate to shut countries out of the USA market if they retaliate against his tariffs. By its second day, the summit had dissolved into chaos, with Trump leaving early and then retracting his endorsement of the final statement from the G7.
A French presidential official, speaking on the condition of anonymity, said that after two days of trying to gain commitments and consensus, all of Europe was sticking to the agreed document. Kudlow suggested on "Face the Nation" that Mr. Trump saw Trudeau as trying to weaken his hand before that meeting, saying the president won't "allow the people to suddenly take pot shots at him".
Kudlow, in a separate TV appearance, said Trudeau was "polarizing" and "really kind of stabbed us in the back".
Donald Trump and Justin Trudeau have been at loggerheads over trade tariffs
Trump, who repeated that his tariffs are meant to protect US 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 pledged retaliatory tariffs against the U.S. starting July 1 because Canadians will "not be pushed around".
In interviews on CNN on Fox News, Trump's top economic adviser, Larry Kudlow, and one of his top aides on trade, Peter Navarro, slammed Trudeau with a series of disparaging adjectives, from "amateurish" to "dishonest", and accused him of a backstabbing "betrayal" of the president.
"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. he 'will not be pushed around.' Very dishonest & weak", he added.
Then, Trump racked up the tension by pointing out the elephant in the room - the absence of Russian Federation, who were suspended from the organisation after their invasion of Ukraine and annexation of the province of Crimea in 2014.
'Trump dictated the letter and I would tell him what he couldn't put in there, ' he said.
US President Donald Trump has told Group of Seven leaders that the United States wants a quick end to trade practices that he says have led to an exodus of American companies and jobs to other countries.
Last year, the USA president was wowed by a French military parade in Paris after being invited to join Mr Macron for his country's annual Bastille Day celebrations.
Germany's Merkel backs restraint with Italy's populist govt
Merkel told lawmakers on Wednesday that Germany will work to ensure that the summit's communique doesn't fall below what was agreed at last year's G-7 and Group of 20 summits.