At the Sunday event, Merkel said that Europeans would continue to work in friendship with the USA, the United Kingdom and others wherever possible, including Russian Federation, but stressed her view that Europeans must be self-reliant, reports CNN.
German Chancellor Angela Merkel on Sunday urged European Union nations to stick together in the face of emerging policy divisions with the U.S., Britain's decision to leave the bloc and other challenges.
Gabriel went on to claim the West had become "weaker", if not "smaller" under the policies of the Trump administration.
The dramatic announcement came after contentious meetings with Trump, who had used his first official trip to Europe to criticize German trade, scold world leaders about their North Atlantic Treaty Organisation spending and refuse to commit to the Paris agreement on combating climate change.
"Anyone who accelerates climate change by weakening environmental protection, who sells more weapons in conflict zones and who does not want to politically resolve religious conflicts is putting peace at risk", Gabriel added.
Gabriel made the remarks on the sidelines of a round-table discussion on migrant crisis in Berlin.
After recent summits, German Chancellor Angela Merkel said May 28 that Europe must take its fate into its own hands.
"And so all I can say is that we Europeans must really take our destiny into our own hands", she said, according to the dpa news agency.
The Social Democrat leader then said it did not matter that Merkel and he were in the middle of an election campaign, as "the chancellor represents all of us at summits like these, and I reject with outrage the way this man takes it upon himself to treat the head of our country's government".
Merkel says Europe can't always trust the USA and United Kingdom going forward.
Steffen Seibert, Merkel's spokesman, addressed the comments at a Monday news conference in Berlin.
The American president backed a pledge to fight protectionism at the end of a summit of the G7 group of wealthy nations on Saturday.
"Those who have accompanied Chancellor Merkel journalistically for a long time know how important the German-American relations are", Seibert said.
'It became clear at the G7, when there was no agreement with the U.S., how long and rocky this path would be, ' Merkel said at a conference on sustainable development. "They were clear and comprehensible".
"Because trans-Atlantic relations are so important to this chancellor, it is right from her viewpoint to speak out honestly about differences, ' he said, stressing that the trans-Atlantic ties 'are a firm pillar of our foreign and security policy".
Germany's exasperation was laid bare after the G7 summit which wrapped up on Saturday with the USA refusing so far to sign up to upholding the 2015 Paris climate accord.
"Here is a situation where it's six, seven if you include the European Union, against one", she said.