"Further, if the alternative means are not finalised shortly, the president will consider re-imposing the tariffs", she said.
Some have said the stand-off should be resolved by reopening talks over a wider EU-US trade deal.
The US administration imposed the tariffs in March on national security grounds.
President Trump's decision puts off a move that could have enraged key American allies at a delicate moment, as the USA heads toward tricky negotiations with North Korea and is considering abandoning the Iran nuclear deal.
Senior US officials are due to travel to Beijing to hold talks on resolving an escalating trade dispute and say they are hopeful of finding a solution but warn the issues are complex.
The US is not expected to allocate licenses under a quota system, though the details of its agreements with other countries are unclear.
Bruce Heyman blames much of the confusion over NAFTA and other issues on the fact that the Trump administration lacks substantive ideas for what it wants to achieve.
The proposed USA tariffs target many products linked to the 2025 plan, but analysts say they are unlikely to make a big difference.
WATCH BELOW: Should Canada demand a permanent exemption from steel tariffs? "Or if they did, then they should be ashamed of themselves because they've destroyed the steel industry, they've destroyed the aluminum industry, and other industries, frankly", he said during the March 1 announcement.
Concerns in recent days centered around whether that exemption would be made permanent.
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The Armenian National Assembly is set to elect new Prime Minister on March 1, a week after Serzh Sargsyan resigned. Armenian opposition leader Nikol Pashinyan attends a rally in Yerevan, Armenia , on April 30, 2018.
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Coupe described the deal as being "designed for a new era" of retailing, bringing scale in clothing and general merchandise. In the fiscal year ended January 31, its global sales rose 1.7 per cent, while its Walmart U.S. division rose 3.5 per cent.
Hours after the USA decision, a foreign affairs spokesman reiterated Trudeau's comments by saying Canada remains confident that the U.S. understands that tariffs would hurt American jobs as much as they would hurt Canadian jobs.
"We gave 30 days and that's all", Navarro said.
Such limited tariffs would not impact Finland very much however, as only two percent of its exported steel and aluminium ends up on the United States market. "Fundamentally, the German government's expectation remains a permanent exemption".
Nucor Corporation CEO and president John Ferriola was among the steel and iron industry representatives who discussed the delay in a press briefing on Tuesday.
South Korea has gained a permanent steel tariff exemption by agreeing to quotas that will cut its steel shipments by about 30% from 2017 levels, but it is still subject to United States aluminium tariffs. Security relationships with the USA have also been part of the criteria.
Trump's embrace of trade barriers this year has sparked fears of tit-for-tat retaliation that could undermine consumer confidence and stymie the strongest global economic expansion in years.
Godelieve Quisthoudt-Rowohl, the EPP group spokesperson on global trade, cautioned, "The US is giving us a little break but the sword of Damocles is still present in trade relations with the EU".
In retaliation to that China threatened to impose a 25% tariff on $50 billion worth of USA exports.
Crippling US tariffs on steel and aluminium are set to take effect on Tuesday, and key trading partners including the European Union have urged the White House to exempt them from the additional cost.
The US deficit in goods with China a year ago was $375 billion, compared to just $83 billion in 2000, before Beijing joined the World Trade Organization.