Trump on Thursday announced his administration would impose a 25 percent tariff on imported steel and a 10 percent on imported aluminium to protect U.S. producers.

South Korea is the third-largest steel exporter to the United States after Canada and Brazil.

"Until the U.S. government makes a final decision, we will actively seek outreach activities toward the United States," South Korea's trade ministry said in a statement.

South Korean trade minister Kim Hyun-chong has been in the United States since Feb. 25, the ministry said. Kim has met U.S. Commerce Secretary Wilbur Ross and other officials to raise concerns over the so-called Section 232 probe and consider a plan that would minimise the damage to South Koran companies.

Shares of South Korean steelmaker Posco fell more than 3 percent on Friday to a four-week low.

Trump is expected to formally announce the tariffs measure next week.

(This story has been refiled to fix typo in para 3)

(Reporting By Jane Chung; Additional reporting by Dahee Kim; Editing by Lincoln Feast)