Trump in his tweet said Trudeau had "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".
In a pointed criticism of Trump's policy, May said that the most effective way of reaping the benefits of globalisation was through multilateral action, adding: "It can not be done by taking unilateral action against your partners".
After Kudlow's comments, Trump added to his string of criticisms against Canada in a series of tweets on Sunday night. He added, "Canadians, we're polite, we're reasonable, but we also will not be pushed around".
The fight isn't just with Trudeau and Canada but with the best allies of the US, Democratic Senator Dianne Feinstein of California said on CNN.
Trump announced on Twitter he had made the decision following comments from Trudeau that Canada would move ahead with imposing retaliatory measures on the USA in response to newly imposed tariffs imposed by the U.S. on aluminum and steel.
The remarks apparently upset Trump, who had left the conference early to travel to Singapore for a highly anticipated meeting with North Korean leader Kim Jong-un.
Less than 24 hours before his meeting with Kim, Trump found time to lambast what he sees as unfair trade practices among the other six industrialized democracies at the summit.
"He is not going to permit any show of weakness on the trip to negotiate with North Korea, nor should he", Kudlow said.More news: Sterling admits he could have been dropped by England
President Donald Trump's top economic adviser says Canadian Prime Minister Justin Trudeau "really kind of stabbed us in the back" when Trudeau said at the end of the Group of Seven summit that Canada wouldn't be pushed around by the USA and its trade tariffs.
Trudeau and the rest of the G-7 failed to seize on Trump's proposal.
German Chancellor Angela Merkel said in a television interview on Sunday that the summit is a "sobering" and "depressing" experience with an outcome that "wasn't a great thing".
However, despite Trump's heated rhetoric, the United States ambassador to Germany, Richard Grenell, has expressed confidence that the trade conflict can be settled, but said it would take some time.
"Well, he holds a press conference and he says the U.S.is insulting". And what did Trudeau do as soon as the plane took off from Canadian airspace?
After Trump's angry tweets, Trudeau's office issued a brief response: "We are focused on everything we accomplished here at the G7 summit".
The prime minister also said Canada would "move forward with retaliatory measures on July 1, applying equivalent tariffs to the ones that Americans have unjustly applied to us".
"So I think Prime Minister Trudeau hit the right note".
"In the name of the Western allies, he ought to come out today and wish President Trump well in the negotiations, instead of taking potshots at us", Kudlow said.
Trudeau fires back on May 31 over the tariffs being applied on the premise Canada poses a national security threat to the U.S.