BERLIN (AFP) - Germany's Foreign Minister Frank-Walter Steinmeier warned on Wednesday (Nov 09) that US foreign policy would become more unpredictable after Donald Trump was elected president, making things "more difficult".

"I think we must expect that American foreign policy will become less predictable for us and we must expect that the United States will be more inclined to make decisions on its own," he said.

"In other words, and I will not dress it up, nothing will become easier, many things will become more difficult," said Steinmeier, who had during the US campaign compared Trump to a "hate preacher" and also described the prospect of him taking the White House as "frightening".

Nevertheless, Germany's top diplomat said he would not give up on transatlantic ties, which he said were "akin to the foundations of the West".

"We must not abandon this foundation," he said, pointing to the traditionally strong diplomatic and people-to-people ties between the two countries.

"Just as we Germans have in the past learnt a lot from our American friends, we should now give encouragement to our American friends to stand with us and to remain part of the partnership that has developed over the years," said Steinmeier.

Separately, Vice Chancellor Sigmar Gabriel said Trump's victory was a "warning to us" ahead of Germany's general elections next autumn where right-wing populists are expected to make inroads.

The chief of the Social Democrats, the junior partner in Chancellor Angela Merkel's right-left coalition, also took aim at the German leader.

He warned against Merkel's push for a "market-oriented democracy", saying that populists could harness anger over a growing social divide in the September 2017 polls.

Defence Minister Ursula von der Leyen meanwhile called Trump's victory a "serious shock" but acknowledged that it was a result "of a democratic election and that we must face up to the reality".