World leaders are walking a fine line as they react to Tuesday’s vote in the United States, congratulating the new president-elect while signalling concern about the billionaire outsider’s rhetoric and policies.

German Foreign Minister Frank-Walter Steinmeier – who proposed the Sunday meeting of foreign ministers – made no effort to disguise his disappointment.

“The result is different to what most people in Germany had hoped to see, but of course we accept it,” he told reporters Wednesday.

“It is good that the election is over, because the way it was conducted has left deep scars. It will not be easy to heal them,” he said. “If Donald Trump really wants to be president for all Americans, as he said this morning, then his first task will be to fill in the deep rifts that developed in U.S. society during the election campaign.”

Mr. Steinmeier then noted the criticism that Mr. Trump expressed toward Europe and Germany during the campaign.

“I think we will have to get used to the idea that U.S. foreign policy will be less predictable for us and we will have to get used to the idea that the U.S. will tend to make decisions on its own,” he said.

The election results likely dash the EU’s hope of concluding a free-trade deal with the United States and are already bolstering opposition parties within Europe who have adopted similar nationalist political messaging to Mr. Trump.

The leaders of the European Council and the European Commission invited Mr. Trump for a separate meeting at the “earliest convenience.”

Since the economic crisis of 2009, global powers have worked through groupings such as the G20 and the Trans-Pacific Partnership to push for deeper integration and freer trade in goods and services. Britain’s June vote to leave the EU marked a break with that direction, driven in part by working-class concerns over jobs, immigration and the flood of refugees entering Europe.

Those same issues have now helped propel Mr. Trump to victory.

Once the results were clear, Mr. Trump stressed the importance of uniting Americans as he addressed his supporters early Wednesday morning in New York.

“I pledge to every citizen of our land that I will be president for all Americans, and this is so important to me,” he said, describing his movement of support as one that includes “Americans from all races, religions, backgrounds and beliefs who want and expect our government to serve the people.”

Mr. Trump’s speech included just a few lines aimed at the rest of the world, but he promised the U.S. under his leadership will seek co-operation in the global community.

“We will get along with all other nations willing to get along with us,” he said. “We’ll have great relationships. We expect to have great, great relationships.”

Canadian Prime Minister Justin Trudeau struck a diplomatic tone in his first public statement congratulating Mr. Trump on his election victory.

“Canada has no closer friend, partner and ally than the United States. We look forward to working very closely with president-elect Trump, his administration and with the United States Congress in the years ahead, including on issues such as trade, investment, and international peace and security,” Mr. Trudeau said.

“The relationship between our two countries serves as a model for the world. Our shared values, deep cultural ties and strong integrated economies will continue to provide the basis for advancing our strong and prosperous partnership.”

Russian President Vladimir Putin, who was praised by Mr. Trump during the election campaign and was accused by Democrats of interference, called for improved relations between the two countries.

“We understand that the way to that would be difficult, taking into account the current state of degradation in the relations between the U.S. and Russia,” Mr. Putin said as he read a prepared statement in the Kremlin.

“And as I have repeatedly said, it’s not our fault that Russian-American relations are in that poor state. But Russia is ready and wants to restore fully fledged relations with the U.S.”

With a report from Reuters