He complained that he had been blindsided by Canadian Prime Minister Justin Trudeau's criticism of his tariff threats at a summit-ending news conference.
Hours after Mr Trump withdrew his support for the joint statement and attacked Mr Trudeau, Mr Kudlow and trade adviser Peter Navarro drove the message home on Sunday morning news shows in an extraordinary assault on a close USA ally and neighbour.
Mexico hit back with fiscal penalties on US exports like pork, steel, cheese and whiskey.
But Sen. Lindsey Graham (R-S.C.) said Sunday on ABC's "This Week", "I'm not so sure John's right about where America is on trade".
The announcement came after the president left the summit, which while in attendance he had announced he wants to put an end to the United States' status as the world's "piggy bank" and suggested eliminating trade barriers between allies.
"That's what weak dishonest Justin Trudeau did", he added. "Our Tariffs are in response to his of 270% on dairy!" the US president tweeted.
Trump said the United States has been subjected to unfair trade duties for many years.
Congo gov't says Jean Pierre Bemba has the right to return home
He said Bemba would probably go to Belgium to meet with his family there before returning to Congo after he is released. Reportedly, three of the five judges decided that he was convicted for crimes which had not been formally accused.
Peter Navarro watches as President Donald Trump speaks before signing Section 232 proclamations on steel and aluminum imports in the Roosevelt Room of the White House on March 8, 2018 in Washington, D.C.
Mr Kudlow accused the Canadian PM of betraying Mr Trump with "polarising" statements on trade policy that risked making the USA leader look weak ahead of a historic summit with North Korean leader Kim Jong-un.
Trump also took aim at North Atlantic Treaty Organisation for relying too heavily on the USA for their security. She also said the European Union would "act" against the USA trade measures.
Canada's foreign minister, Chrystia Freeland, said her country "does not conduct its diplomacy through ad hominem attacks".
"He was polarizing", Kudlow said during a Sunday morning appearance on CNN's "State of the Union".
Despite Trump's comments, Russian Foreign Minister Sergei Lavrov said on Saturday that Moscow was perfectly happy working with the larger G20 and had "never asked anyone to return" to the Group of Seven.
He said Trump "did the courtesy to Justin Trudeau to travel up to Quebec for that summit".
The two-day 44th G7 summit ended on Sunday.