"They are (Canada) very restrictive as to taking our agricultural product and other things", he said.
Trade war fears between the United States and its trading partners have been rife since March.
The administration is taking the action under a relatively obscure USA trade law meant to protect national security.
Malmstrom is meeting U.S. Trade Representative Robert Lighthizer in Paris on Thursday among other global trade chiefs.
Fears of a global trade war are overshadowing the G7 talks in the Canadian resort town of Whistler, as Washington's allies vow to push back against the US decision on tariffs. "If Americans got all their clothing, all their food, all their goods and services for free, they still couldn't compete with other countries because the economy has been so financialized that American labor has been priced out of world markets".
Germany's Volkswagen, Europe's largest carmaker, warned that the decision could start a trade war that no side would win.
"But if you take the European Union and you see the kind of tariff they charge, and then we don't, that's called "not fair trade".
"Any government that embarks on a protectionist path inflicts the most damage on itself", he added.
Asked if the United States was isolated on the issue of tariffs in the G7 talks, Dombrovskis said: "Indeed".
After the measures were announced on Thursday, the UK's worldwide trade secretary Liam Fox also dismissed Mr Trump's claim that the tariffs were for security reasons.
Foreign Affairs Minister Chrystia Freeland, who pushed the steel and NAFTA issues during her meeting on Tuesday in Washington with USA trade czar Robert Lighthizer, has also made it clear that Canada would retaliate if the duties are imposed. But they can also increase costs more broadly for US manufacturers who cannot source all their needs locally and have to import the materials.
Canadian Finance Minister Bill Morneau said he told Mnuchin it was "our absolute view that this is absurd that Canada could in any way be a security risk". But he exempted Canada, Mexico and the European Union to buy time for negotiations - a reprieve that expired at midnight Thursday.
"The move, which has been threatened for months, is nearly certain to draw response from the European Union, which has threatened to retaliate with its own tariffs on such American products as motorcycles, jeans and bourbon", the daily said.
The EU earlier threatened to counterpunch by targeting USA products, including Kentucky bourbon, blue jeans and motorcycles.
They said the announcement was planned for Thursday morning in Washington but that the timing could still change.
Some observers say a G6-plus-one scenario is already shaping up, with U.S. President Donald Trump as the outlier.
Following the conclusion today of a three-day meeting of G7 finance ministers in Whistler, B.C., Finance Minister Bill Morneau issued issued a chair's summary that says the other six members want Trump to hear their message of "concern and disappointment" over the USA trade actions.
The world's two biggest economies have threatened to impose tariffs on up to United States dollars 200 billion worth of each other's products.
The U.S., Canada and Mexico have been holding talks to renegotiate the deal.
Trump's imposition of tariffs on America's largest foreign providers of the crucial metals - the European Union and Canada are the largest United States exporters of steel and aluminum respectively - upended the agenda for this normally convivial event for consensus-building among countries which account for about half of global GDP.
The finance ministers of the six countries, who participated in the G7 Finance Ministers Meeting in Whistler, Canada, along with US Treasury Secretary Steven Mnuchin have threatened to impose their own set of tariffs on American goods.
- Can Manchester United win the Premier League this season?
- IOS 12! New Macs! Catch our WWDC '18 predictions on The CultCast
- School shooting video game removed online after backlash
- South China Sea dispute: Mattis says China 'intimidating neighbours'
- Officials got it right on charge call at end of Game 1
- Junket tourism
- Health minister favours warnings on cigarettes as feds outline tobacco strategy
- India, Pakistan trade fire in Kashmir; 2 dead, 8 wounded
- Belgium: Gunman kills two police officers, civilian, shot dead in Liege
- Talks held in Italy amid political crisis