Mocking his manhood, Keith wrote in his autobiography Life about the singer's little 'todger' and that Marianne Faithfull had 'no fun' when she was sleeping with him in the '60s.
But Elton has now defended his friend.
The 63-year-old told Rolling Stone magazine: 'I was a bit put off by hearing about Mick's penis. I'm a big Mick Jagger fan... If I said that [co-songwriter] Bernie Taupin was a miserable c*** and had a small penis, he'd probably never talk to me again.
'It's like, 'Why do that?', especially with someone you're in a working relationship with.'