UN Secretary-General Ban Ki-moon voiced confidence on Friday that Donald Trump will shed the strident rhetoric that propelled him to the White House and engage with the world to confront global crises like climate change.

Ban told AFP in an interview that he hopes to meet with the US president-elect in the coming weeks to explain how the United Nations expects the United States to "continue to work for humanity."

Trump won the US presidency on a platform that calls for closer ties with Russia, pulling out of the Paris climate deal, shaking up security alliances and questioning US funding of the United Nations.

"This is what he said during the campaign period, on the campaign trail," Ban said in the interview at UN headquarters where the Trump victory has shocked world diplomats.

"Now, post-election, when he creates his transition team with experts and people with vision and expertise, I am sure that the United States will continue to play a leading role," he said.

Ban spoke by phone with Trump on Friday afternoon and the two men agreed to stay in contact, said a UN statement.

- Worrying statements -

Ban, 72, is stepping down on December 31 after 10 years as the world's diplomat-in-chief with the biggest success of his tenure under threat: the Paris climate agreement.

During his campaign, Trump described global warming as a hoax invented by the Chinese, vowing to renege on US pledges to cut down greenhouse gas emissions and help finance the shift to a new green economy worldwide.

"He has made a lot of worrying statements, but I am sure that he will understand the whole importance and seriousness and urgency," he said.

"The presidency may be important, but humanity and all our lives and our planet Earth are eternal."

Ban argued that there was a strong consensus in the United States and across the world on the need to address global warming, suggesting Trump would be recklessly out-of-sync if he scrapped the deal.

"Now business communities are fully on board. Civil society members are fully on board. How can one change all this course? It's a huge trend," he said.

"It will create serious problems if anybody wants to undo it, or unravel all this process."

The interview was Ban's first full assessment of the impact of the Trump electoral victory on global diplomacy.

- Real values -

The UN chief watched the election results unfold on Tuesday from his Manhattan home and retired just as news channels were beginning to predict a Trump win.

"I got up at 4:00 am and I found that the whole world had changed," said Ban. He described the outcome as "quite a surprise."

He brushed aside the suggestion that the United States, by far the biggest financial contributor to the United Nations, could cut funding or sidestep the world body in addressing global issues.

"I am not much worried, much concerned about what has been talked (about) during the electoral process," he said.

The former South Korean foreign minister was elected UN chief in 2006 with strong backing from the United States under the Republican presidency of George W. Bush.

Ban expressed gratitude to Bush for agreeing to UN-led talks on climate change even though it was a long road to the Paris accord reached in December last year and now signed by all 193 UN member-states.

While Trump has yet to outline his policies, Ban sought to downplay anxiety over a new world order under his presidency, saying all US administrations since the founding of the United Nations after World War II have been committed to core principles.

"As I have seen in all many different presidencies," Ban said, "there has not been much difference when it comes to real values and principles for the United Nations charter -- and for humanity."