It's OK to make fun of God as long as the joke is not offensive, Pope Francis said on Friday in a special audience with about 100 comedians, actors and writers from around the world.

Those meeting him at the Vatican included US showbiz celebrities Whoopi Goldberg, Jimmy Fallon, Conan O'Brien, Chris Rock and Stephen Colbert. Around two-thirds of the guests were Italians.

"Can we also laugh at God? Of course, it's not blasphemy, we can, just as we play and joke with the people we love," Francis said, speaking in Italian.

"Humour does not offend, humiliate, or put people down according to their flaws," he added, holding up "Jewish wisdom and literary tradition" as an example of good comedy.

The pontiff made the remarks after himself coming under fire, and apologising, for the use of an insulting word towards gay people.

"What I am saying now is not heresy: when you manage to draw knowing smiles from the lips of even one spectator, you also make God smile," Francis said.

The 87-year-old went a little off-script during the 30-odd-minute meeting, colouring his speech with a clownish gesture, and adding to it a seemingly sexist remark.

Talking about Sarah, the wife of Abraham in the Old Testament, he said she was "nosy like women", as she would spy on her husband to "perhaps" later scold him.

After his speech, Francis greeted each participant, cracking jokes, receiving gifts including a bottle of Italian liquor, and posing for a selfie with Pio and Amedeo, an Italian comic duo.

Interactions with non-Italian speakers were more limited.

"Well it was brief, he spoke in Italian, so I'm not quite sure what was said," late-night TV host O'Brien said with a smile, before adding that he had been given an English translation of the speech.

O'Brien jokingly compared lining up to shake the pope's hand to children waiting to meet Santa Claus.

"I wanted to sit on his lap (and say): 'I want a sleigh for Christmas', you know? 'I want a basketball!'..."

"It was quick ... I had a wonderful time", O'Brien added.

The pontiff later flew to southern Italy to take part in G7 discussions on artificial intelligence.