Instead of telling Trump directly, Trudeau waited until the President was departing the summit, then told reporters in a news conference that he meant to press ahead with retaliatory tariffs against United States products, declaring that Canada "will not be pushed around".
'I used language that was inappropriate and basically lost the power of that message, ' says Navarro.
Navarro offered an apology at the Journal's CFO Network event.
Trump followed up on Sunday with tweets calling free trade with Canada "fools trade" and said Trudeau "acts hurt when called out".
In contrast, Trump was incredibly friendly during his historic meeting with Kim in Singapore on Tuesday, even giving the North Korean leader a thumbs-up.
Navarro, for his part, suggested that he was following orders - but made a poor choice of words in doing so.
"The problem was that in conveying that message I used language that was inappropriate", he said.
"I own that, that was my mistake, those were my words".
"Canadians, we're polite, we're reasonable, but we also will not be pushed around", Trudeau said Saturday as the gathering concluded after Trump had left early for the Singapore summit with Kim Jong Un.
"On (Trump's) comments, I'm going to stay focused on defending jobs for Canadians and supporting Canadian interests".More news: US Attorney General excludes domestic, gang violence from asylum claims
Trump's most recent salvo came in a series of tweets from Singapore late Sunday, where he again blasted Canada for charging a 270 per cent tariff on US dairy imports, and levelled more personal attacks at Prime Minister Justin Trudeau.
While Trump expressed surprise at Trudeau's remarks, his comments were largely in line with what Canadian officials had said since Trump's announcement of tariffs.
"When I got on to the plane, I think that Justin probably didn't know that Air Force One has about 20 televisions", Trump said.
"Why should I, as President of the United States, allow countries to continue to make massive trade surpluses, as they have for decades, while our farmers, workers and taxpayers have such a big and unfair price to pay?"
Trump and Kim shook hands and posed for photos before their almost 40-minute one-on-one conversation behind closed doors.
"Canada does not conduct its diplomacy through ad hominem attacks ... and we refrain particularly from ad hominem attacks when it comes from a close ally", Ms Freeland told reporters in Quebec City.
Mr Trump has infuriated the European Union, Canada and Mexico by imposing tariffs on steel and aluminium imports.
"Very childish and unprofessional behaviour", Gorka said. "I had a very good meeting with the G-7".
Alberta's economic development minister says Canada has to stand up to U.S. President Donald Trump's trade threats.
The U.S. has been negotiating a new NAFTA agreement with Canada and Mexico since previous year, but recent tensions over trade tariffs have interfered in NAFTA talks.