International Trade Secretary Liam Fox, who is to visit Washington next week to seek further detail on the planned levies, said it would be "absurd" for the United Kingdom to be included in Mr Trump's tariffs.
"Any tariffs imposed on United Kingdom steel by President Trump on a scale that is being mooted would be misguided and deprive USA manufacturers of some of the most specialist steel in the world".
China also expressed its "firm opposition" to the tariffs Friday.
West Australian Premier Mark McGowan said he believed Mr Trump's actions could still have some unforeseen and wide-ranging consequences, given the state exports iron ore to countries like China and Japan.
"We should prevent a trade war situation from excessive protectionism, in which the entire world harm each other", Trade Minister Paik Un-gyu told a meeting with steelmakers.
Trump said the "aggressive" foreign trade amounted to an "assault" on the USA, but that he would also show flexibility with friendly countries, possibly removing tariffs for some.
Within minutes of the announcement, U.S. Republican Senator Jeff Flake, a Trump critic, said he would introduce a bill to nullify the tariffs. But it added that it will "do its best" to get on the list of countries that are exempt from the restrictions. And Trump took note of U.S. Steel's announcement that it planned to ramp up activity at its plant in Granite City, Illinois, and recall about 500 employees because of the new tariffs. Navarro is known as a strident critic of the trade policies of both Germany and China. "Global steel producers who have previously exported to the U.S. no longer can, because the prices are too high as a result of the tariffs", he added.
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It said it would study the move's impact on Japanese companies before responding further. "Consumers are just beginning to see more money in their paychecks following tax reform, but those gains will soon be offset by higher prices for products ranging from canned goods to cars to electronics". The largest steel importers to the USA are Canada, Brazil, South Korea, and Mexico. The tariffs may also start a chain reaction of retaliation around the world; the European Union is already suggesting duties on United States goods like bourbon and Harley-Davidson motorcycles.
Malmstrom said she would be meeting with U.S. Trade Representative Robert Lighthizer in Brussels on Saturday.
In addition to Trump, Trudeau spoke to U.S. House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell.
Brussels is also looking to "safeguard" measures to protect its industry - restricting the bloc's imports of steel and aluminium to stop foreign supplies flooding the European market, which is allowed under World Trade Organisation rules. By getting tough on steel tariffs ostensibly to protect national security, the cost might be alienating some of the nation's closest military and diplomatic partners.
The EU represents many top USA trading partners, including Germany, the UK, France and Italy.
President Trump's plan to impose tariffs on steel and aluminum imports seems to change by the minute, but the latest signal may have tripped up Thursday's stock market rally.
Canada and Mexico have both been exempted from the provisions during negotiations on the revision of the North America Free Trade Agreement (NAFTA) in order to pressure the two countries into bowing to United States demands.
What happens if the talks fail?Canada and Mexico are the only two countries exempted, for now.
"Mexico reiterates that the negotiation of NAFTA should not be subject to conditions outside the process", it added.
China is just America's 11th-biggest supplier of foreign steel and the fourth-biggest supplier of aluminum.