The dispute has fuelled concerns that soybeans, the United States' most valuable export to China, might be caught up in the row after Beijing launched an inquiry into imports of U.S. sorghum, a grain used in animal feed and liquor.
President Donald Trump, who has broad powers to impose the tariffs of 25 per cent on steel imports and 10 per cent on aluminium, at the outset granted exemptions to Canada and Mexico, and said there would be the possibility of industry exemptions, although he has not been specific.
European Union, Japanese and USA trade officials confer at EU headquarters in Brussels, March 10, 2018.
Trump said the tariffs, which will come into effect after 15 days, will not initially apply to Canada and Mexico.
"We call for calm-headed behaviour", Mr Seko said.
The European Union will go to the World Trade Organisation to impose its own measures if the bloc is not excluded from the USA steel and aluminum tariffs, EU's trade chief said on Friday.
Trump, who cited a rarely invoked national security section of USA trade law as the legal basis for his decision, said he aims to protect the United States industries.
"An industry that can't make it, we have to protect a macroscopic number of workers at the expense of 330 million American people", RealClearMarkets editor John Tamny told FOX Business' Charles Payne.
She said she got "no immediate clarity on the exact US procedure for exemption" and that new talks are planned for next week.
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In reaction, Iranian lawmaker Ramezan-Ali Sobhanifar said, "Considering the fact the United States is a major consumer of steel, the tariff increase could push major steel producers to look for new markets".
Third, the manner in which Mr Trump unveiled his tariffs underscored his unpredictability.
European Commission Vice-President Jyrki Katainen told AFP on Friday the bloc could form a "coalition of like-minded countries" to file a complaint at the WTO, though this procedure usually takes around two years.
The Chinese Commerce Ministry called Trump's tariffs "a serious attack on normal worldwide trade order" and said that Beijing is "firmly opposed" to the measures.
Brussels is also looking at "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 Organization rules.
It has already started monitoring incoming metal flows to see whether a surge occurs.
Tamny states the tariff plan is meant to protect a minimal amount of jobs in the US while making consumers pay more.
The EU is also maintaining a threat of counter-measures that would target USA imports ranging from maize to motorcycles, and may publish its list next week to allow industry and other interested parties to give their input.
The trade chiefs of the European Union and Japan are holding talks about U.S. President Donald Trump's plans to impose tariffs on steel and aluminum amid fears they could trigger a broader trade war.