She also pledged to raise spending for humanitarian and development aid
Chancellor Angela Merkel on Monday said Germany must "stand fast, argue, and fight for our own convictions" and assume greater responsibilities at a time when multilateralism is coming under intense pressure.
In her New Year's address to Germans, Merkel said long-held certainties about international cooperation were being put to the test.
Global challenges including climate change, immigration and the fight against terrorism could not be solved by countries going it alone, she warned.
"For our own interests, we want to solve all these questions, and we can do that best when we also take into consideration the interests of others," she said in a speech to be broadcast in full later Monday.
"That is the lesson from two world wars of the last century," she said, warning however that "certainties about international cooperation is falling under pressure."
"In our own interest, we must take on more responsibilities," she said.
With an eye to Germany taking on a non-permanent seat in the UN Security Council in 2019 and 2020, the leader of Europe's biggest economy said her country would push for "global solutions."
She also pledged to raise spending for humanitarian and development aid, as well as defence.
Although Merkel did not name US President Donald Trump in her speech, she has on previous occasions rejected his criticisms of multilateralism.
In his second appearance before the UN's annual gathering in September, Trump told the General Assembly that he and his administration "reject the ideology of globalism, and we embrace the doctrine of patriotism."
A week later, Merkel had warned Trump against "destroying" the UN.
"I believe that destroying something without having developed something new is extremely dangerous," Merkel said at a regional election campaign event then.