In a statement, the White House said that Argentina, Australia and Brazil would be exempted from the 25% tariff on steel imports and 10% on aluminium, which Trump announced earlier this year.
The temporary exemptions for these countries were set to expire on Tuesday this week.
The White House statement said: “The administration is also extending negotiations with Canada, Mexico and the European Union for a final 30 days.
“In all of these negotiations, the administration is focused on quotas that will restrain imports, prevent transhipment, and protect national security.”
Trump has also granted permanent exemption on the tariffs to South Korea. The EU has warned it would retaliate if it was not exempt from the tariffs.
Last week, the bloc’s trade chief Cecilia Malmstrom said the German chancellor and French president would press the US to permanently exempt the union from the tariffs, during their separate visits to Washington.