"These unilateral tariffs, imposed under a false pretext of safeguarding US national security, are inconsistent with the United States' worldwide trade obligations and WTO rules", Foreign Minister Chrystia Freeland said in a statement.
White House economic adviser Larry Kudlow likened the Trump administration's dispute with the Canadian government to a "family quarrel" during an interview on Fox News Sunday.
"This measure will be in force for as long as the United States government maintains the imposed tariffs", the ministry said.
Trudeau last week slammed the Trump administration's decision, calling the tariffs an "affront" to the historic alliance between the two nations.
Following Saturday's conclusion of a three-day meeting of G7 finance ministers, Canadian finance minister Bill Morneau issued a summary saying the other six members want Mr Trump to hear their message of "concern and disappointment" over the United States trade actions. "That is not Free or Fair Trade, it is Stupid Trade!" the president said on Twitter.
He said that events next week "will depend on the decision the [US] administration is ready to take in the next few days and in the next few hours - I'm not talking about weeks ahead".
"I don't think in any way the U.S.is abandoning its leadership in the global economy, quite the contrary".
Just before the G7 summit ended, Trump tweeted that "the United States must, at long last, be treated fairly on trade". But a Business Insider analysis found that the Canadian tariffs could apply to $15 billion or more in US goods.
Mnuchin, however, downplayed the disagreements and said the United States was committed to the G7 process.
Canada and Mexico, which are embroiled in talks with the United States to update the North American Free Trade Agreement, responded to the USA move by announcing levies of their own on a variety of American exports.
Chairing the meeting, Mr Morneau allowed participants to register grievances with Mr Mnuchin one at a time, according to a Canadian source.
With President Donald Trump about to visit Canada for a G7 meeting, and a conference on U.S. "The U.S. has been ripped off by other countries for years on Trade, time to get smart".
They apply to items such as plated steel, slabs, coil, rolls of aluminium and tubes - raw materials that are used extensively across USA manufacturing, construction and the oil industry. "Highly restrictive on trade!" he wrote.
According to Ross, the step followed months of unsuccessful talks between the U.S. and its two neighbors over changes to the North American Free Trade Agreement (NAFTA). "When you're nearly 800 Billion Dollars a year down on Trade, you can't lose a Trade War!" "We actually buy a lot of USA steel, bring it into Canada turn it into something else and send it back to the United States so we're actually helping the USA economy so we're one of the innocent bystanders stuck in the middle".
"I've taken a different take on that than my father", Trudeau told Todd Sunday.