The Pontiff was speaking in his annual state of the world address and said it was “paramount importance to support dialogue on the Korean peninsula” to overcome “current disputes”.
His call for peace comes just days after despot Kim Jong-un sent a chilling message to the US warning his nuclear launch button is always within reach of his desk.
Mr Trump then continued the pair’s war of words and tweeted: “I too have a Nuclear Button, but it is a much bigger & more powerful one than his, and my Button works!”
Quoting Pope John XXIII at the height of the Cold War, the Pope said: “Nuclear weapons must be banned. There is no denying that the conflagration could be started by some chance and unforeseen circumstance.”
The pope addressed envoys from almost 200 countries just one day before North and South Korea are due to begin talks for the first time since 2015.
Delegations from the two countries are expected to address North Korea’s participation in the Pyeongchang Winter Olympics.
He also noted the Vatican was among 122 states that agreed to a United Nations treaty to ban nuclear weapons.
After the speech, Pope Francis spent more time chatting with South Korea’s envoy, Jonghyu Jeong, than with most other diplomats, reports Reuters.
The Pope’s words come amid a potential thaw in tensions on the Korean Peninsula.
North and South Korea are to begin talks tomorrow over the rogue North’s attendance at the Pyeongchang Winter Olympics.
A team of delegates from both nations will meet at the border truce village of Panmunjom.
The last time the two Koreas engaged in official talks was in December 2015.
However there are concerns the North could use the Olympics to drive a wedge between Washington and Seoul, and it will use the sporting event to bargain against international sanctions.
US President Donald Trump on Thursday called the proposed inter-Korean talks a “good thing,” and he and his South Korean counterpart Moon Jae-in announced that annual large-scale military drills would now take place after the Olympics.
Mr Trump took credit for any dialogue that takes place, tweeting: “Does anybody really believe that talks and dialogue would be going on between North and South Korea right now if I wasn’t firm, strong and willing to commit our total ‘might’ against the North.”