"Maintaining the principle of free trade is vital for sustainable economic growth and the principal should be fully respected," Kosei Shindo, chairman of the Japan Iron and Steel Federation, said in a statement.

Japan's steel industry will study the impact of the tariffs, and would continue to advocate for the adoption of policies based on the principle of free trade, he added.

The comments came after U.S. President Donald Trump pressed ahead with the imposition of a 25 percent tariff on steel imports on Thursday, but exempted Canada and Mexico.

(Reporting by Yuka Obayashi; editing by Richard Pullin)