Hollywood star Russell Crowe has apologised after an apparent anti-circumcision tirade on Twitter, while a Jewish friend he was exchanging tweets with has defended him.

While the friend said the remarks had been blown out of proportion by journalists, the Oscar-winning actor took down a series of entries on his Twitter feed from Thursday, and said he was sorry to anyone he had offended.

"I have a deep and abiding love for all people of all nationalities. I'm very sorry that I have said things on here that have caused distress," he wrote on the microblogging website.

"My personal beliefs aside, I realise that some will interpret this debate as me mocking the rituals and traditions of others. I am very sorry."

In the original tweets, reported by the Hollywood Reporter among others, he wrote: "Circumcision is barbaric and stupid. Who are you to correct nature? Is it real that GOD requires a donation of foreskin? Babies are perfect."

But Jewish film director Eli Roth, with whom he had been exchanging tweets, came to his defence, saying Crowe was "one of the nicest people I have ever been lucky enough to meet and work with. AND RESPECTFUL OF ALL RELIGIONS."

Speaking to celebrity news website TMZ, Roth lashed out at a headline that said Crowe "insults Jews".

"The headline blatantly attempts to make Russell look like an anti-Semite. It's tabloid journalism at its worst," he said.

"No one contacted either of us. It's terrible. Russell is a great person and respectful of all religions ... The press is trying to terrify celebrities into not using Twitter. They want to show they can still ruin you. It's sickening."

A spokesman for New Zealand-born Crowe, the Gladiator and Robin Hood star who has lived in Australia since his youth, did not immediately respond to requests for comment.

- AAP