Switzerland's foreign minister said on Friday that his country will continue to strive for an agreement with the United States after the White House announced a higher 39% tariff on Swiss imports in an escalating trade war between the two countries.

"It is with great regret that we had to take note of President (Donald) Trump's new decision on tariffs," Swiss foreign minister Ignazio Cassis said in an address at a Swiss National Day event.

"We are not discouraged and continue to strive for an agreement in the interests of both sides," he added.