“We can no longer completely rely on the White House,” Heiko Maas told the Funke newspaper group.
“To maintain our partnership with the USA we must readjust it. The first clear consequence can only be that we need to align ourselves even more closely in Europe.”
Maas said Europe “must not let itself be divided”, however “sharp the verbal attacks and absurd the tweets may be”.
Maas’ comments come a day after Trump said in a CBS interview that the EU was a “foe”.
“Well, I think we have a lot of foes … Now you wouldn’t think of the European Union, but they’re a foe,” he said in an interview with the Face the Nation that aired on Sunday.
He added that the EU has “really taken advantage of us on trade” though this “does not mean that they are bad”.
The US president also called Russia and China foes, but said such a label does “not mean they are bad”.
“It doesn’t mean anything,” he said. “It means that they are competitive.”
Germany’s European affairs minister, Michael Roth, appealed for unity on Monday as he accused Trump of “provoking” a response Europe.
“He is trying to bring about a split in the EU. He is describing us as enemies. We do not see it like that at all,” Roth said, speaking of the “deep and close partnership”.
He said the EU should not be unsettled by Trump’s “in part very aggressive, untruthful and not particularly constructive” comments, noting that “indignation alone will not help us”.
“The only thing that helps is clear language, and a clear united position,” the minister added.
In response to Trump’s remarks, European Council President Donald Tusk said the EU and the US are “best friends”.
“Whoever says we are foes is spreading fake news,” Tusk, who is also a former Polish prime minister, wrote on Twitter on Sunday.
On Monday, EU foreign policy chief Federica Mogherini said that “for sure, we consider the United States friends, partners – close friends and partners”.
“We have very clear in mind who our friends are: the United States for sure,” she said.
“A change in the administration doesn’t change the friendship between countries and peoples.”
The US president has been feuding with European leaders in recent weeks, and the controversy burst out into the open during last week’s NATO Summit, where he accused Germany of being “captive” to Russia, and criticised other European allies for not paying for their defence.
In Sunday’s interview, Trump again complained “it’s a very bad thing for Germany” that the country depends on Russian gas, for which it is paying “billions” to Moscow.
Trump is sitting down with Russian President Vladimir Putin on Monday.
The United States also recently imposed tariffs on steel and aluminium against the EU and other allies, sparking retaliation.
A trade war is also under way with China after the US implemented tariffs for what it called unfair trade practices by Beijing.