US Secretary of State Marco Rubio will visit Rome and the Vatican this week, an Italian government source said Sunday, just weeks after a clash between Donald Trump and Pope Leo.

Rubio, who is a Catholic, is expected to meet Vatican Secretary of State Pietro Parolin and Italian Foreign Minister Antonio Tajani, the source told AFP.

Italian media reported that he would also meet Defence Minister Guido Crosetto during the Thursday-Friday visit.

The meetings come several weeks after US President Trump's extraordinary criticism of Pope Leo XIV over the Catholic leader's anti-war rhetoric.

Trump also dismissed Italian Prime Minister Giorgia Meloni -- one of his closest European allies -- as lacking courage after she defended the US pontiff.

Italian media on Sunday presented Rubio's visit as a meeting to "thaw" relations.

Since taking over as leader of the world's 1.4 billion Catholics on May 8, 2025, following the death of Pope Francis, Leo has criticised the Trump administration's crackdown on immigration.

But it was his increasing anti-war rhetoric, particularly following the US-Israeli attack on Iran, that triggered Trump's ire.

Leo on April 7 declared Trump's threat to destroy Iran "unacceptable" and urged Americans to demand that US lawmakers "work for peace".

The US president subsequently slammed the pontiff in a social media post as "WEAK on Crime, and terrible for Foreign Policy".

Trump also said he was "not a big fan of Pope Leo" and that he does not "want a pope who thinks it's OK for Iran to have a nuclear weapon."

Meloni condemned as "unacceptable" Trump's criticism -- prompting the president to turn his fire on her.

"I'm shocked at her. I thought she had courage, but I was wrong," the US president said in an interview with Italian daily Corriere della Sera.

He also accused Meloni -- a far-right leader who has sought to act as a bridge between diverging US and European views -- of failing to help the United States with NATO.

Trump has threatened to pull US troops from Italy, saying Rome "has not been of any help to us" in the Iran war.

He has made a similar threat towards Spain, while the Pentagon has announced it is withdrawing 5,000 US troops from Germany.