Navarro later apologized for the comments, telling a news conference in Washington on Tuesday: "My job is to send a signal of strength".
"I used language that was inappropriate and basically lost the power of that message", he said.
President Trump may be fresh off a meeting with North Korean leader Kim Jong-Un, but he's still smarting from a perceived slight from Canadian Prime Minister Justin Trudeau. "That's what weak, dishonest Justin Trudeau did", said Navarro, referring to the joint press conference that is routinely held at the end of the annual events.
The president's staff then blasted Trudeau on Sunday with economic advisor Larry Kudlow accusing Canada of stabbing the U.S.in the back.
"I want to pay a particular tribute to Prime Minister Trudeau for his leadership and skilful chairing, which enabled us after two days of negotiation between leaders to agree actions and a shared approach on some of the most pressing challenges facing the global community and our citizens", she said.
"That's going to cost a lot of money for the people of Canada", the irate president said.
Angela Merkel speaks with Donald Trump at the G7 meeting
He asserted, with no evidence, that Trudeau only dared to say Canada wouldn't be pushed around because he didn't think Trump, who was on board Air Force 1 en route to Singapore, would see him. Other than he had a news conference because he assumed I was on an airplane and wasn't watching.
The horror! Who could have predicted that when Trump imposed steel and aluminum tariffs against Canada - citing national security concerns - the Canadians wouldn't be happy and might strike back?
Trudeau also said he would stand up for Canadians. But more importantly, he should apologize to the Canadian public.
Foreign Minister Chrystia Freeland warned Tuesday that Canada is prepared for anything, even as the US considers auto tariffs that experts say would lead to a full-out trade war, harming both Canadian and American businesses.
REMINDER: This is Canada we're talking about.
Freeland said she had a "good conversation" Sunday with US Trade Representative Robert Lighthizer, and that the pair would try to meet in Washington this week.
Trudeau has declined to directly respond to Trump's criticism of him.
In Vermont, where Trump is particularly unpopular, a few choice words from the president won't keep people away from a popular weekend getaway on either side of the border, says one keen observer.
Macedonia agrees to new name after 27-year dispute with Greece
Following the latest round of discussions, Macedonia is now set to be known as the Republic of Northern Macedonia . The deal still needs to be approved by the Macedonian and Greek parliaments. "I am keeping my fingers crossed".