The pontiff cited Norway as a country that could help negotiate a solution to US-North Korea crisis
Pope Francis says a third country should try to mediate in the dispute between North Korea and the US.
He says someone needs to cool a situation that has become "too hot" and poses the risk of nuclear devastation.
He picked Norway as an example of a country that is "always ready to help".
Speaking to reporters on his plane while returning from a trip to Europe, Pope Francis also called on the United Nations to reassert its leadership as the organisation had become “watered down”.
In comments quoted by Reuters, the pontiff suggested: "The path is the path of negotiations, of a diplomatic solution.
"We are talking about the future of humanity. Today, a widespread war would destroy - I would not say half of humanity - but a good part of humanity, and of culture, everything, everything."
He added: "It would be terrible. I don't think that humanity today would be able to withstand it."
His comments come a day after North Korea test-fired another ballistic missile, which the US and South Korea say exploded shortly after take-off.
Donald Trump has warned that a "major, major conflict" with North Korea is a possibility.
The Trump administration has repeatedly called on China to assist efforts to impose sanctions and other restrictions against Pyongyang.
Speaking on Friday, US Secretary of State Rex Tillerson said China's role is "particularly important" due to the country's economic leverage over North Korea.
At a rally last night, President Trump told supporters: "We have somebody [in North Korea] who is causing a lot of trouble for the world.
"We have China, who is really trying to help us. You've seen they've sent back vast amounts of coal coming out of North Korea. So let's see what happens."
Meanwhile, the controversial Philippines leader Rodrigo Duterte called on President Trump to avoid tensions escalating.
Duterte - who has been heavily criticised internationally for encouraging a violent war against drugs in his country - told reporters: "I’m expecting a call actually from President Trump tonight, and who am I to say that you should stop.
"But I would say, Mr President, please see to it there is no war, because my region will suffer immensely."
Following the phone call, the White House said President Trump had invited President Duterte to visit Washington.