In urging Trudeau to apologize for his comments, he also said the prime minister's statements were a "diplomatic betrayal" as Trump headed to Singapore to his high-profile summit with North Korean leader with Kim Jong-un.
Canadian Prime Minister Justin Trudeau said all global leaders at the meeting signed the agreement during a press conference where he stood firmly on new retaliatory tariffs to answer for Trump's tariffs on aluminum and steel that were "unjustly applied to us".
Trudeau also said Canada "will not be pushed around" byt its mighty US neighbor.
Trump swiftly responded to Trudeau by upending the communiqué in a series of tweets Saturday evening.
The move enraged Trump, who branded his Canadian counterpart "dishonest and weak" in a furious tweet, announcing the USA would pull out of an agreed communique.
Asked what Trudeau did that amounted to betrayal, Kudlow criticized the Canadian leader for holding a press conference in which he called US tariffs "insulting".
"He really kind of stabbed us in the back", Mr. Kudlow told CNN's State of the Union.
Mr Trump called Mr Trudeau "dishonest & weak" after Mr Trudeau said at a news conference that Canada would retaliate for new USA tariffs.
He did him a favour and he was even willing to sign that socialist communique.
Kudlow said that Trudeau's press conference criticisms of Trump's trade tariffs were inappropriate. "We will stand by them and anyone who would depart from them, once their back was turned, shows their incoherence and inconsistency", the statement said.
It comes after Trudeau explained his position at a news conference in which he outlined the difficulties in moving forward with the North American Free Trade Agreement.
"They should have said to him, 'God speed, you are negotiating with the insane nuclear tyrant in North Korea, and we are behind you, '" Kudlow added. "Prime Minister Trudeau may reap some political benefit through feuding with President Trump, but by engaging with the President on the terms he has so far, instead of on mutually productive ones, he is imperiling the economic well-being of millions of Canadians and Americans".
"I have made it clear to [President Trump] that it is not something we relish doing, but it is something that we absolutely will do", Trudeau said.