In his new book Then It Fell Apart, Moby said the pair met when she was 20 and he was 33, and that the two dated briefly, before Portman broke it off.
But in a recent interview with Harpers Bazaar, Portman said she was 'surprised to hear that he characterized the very short time that [she] knew him as dating', adding that her 'recollection is a much older man being creepy with [her] when [she] just had graduated high school'.
"He said I was 20; I definitely wasn't. I was a teenager," Portman said in the interview. "I had just turned 18. There was no fact checking from him or his publisher - it almost feels deliberate.
"That he used this story to sell his book was very disturbing to me. It wasn't the case. There are many factual errors and inventions. I would have liked him or his publisher to reach out to fact check.
"I was a fan and went to one of his shows when I had just graduated. When we met after the show, he said, 'let's be friends'. He was on tour and I was working, shooting a film, so we only hung out a handful of times before I realized that this was an older man who was interested in me in a way that felt inappropriate."
Moby responded to Portman's assertions in an Instagram post he shared earlier today, writing: "I recently read a gossip piece wherein Natalie Portman said that we'd never dated. This confused me, as we did, in fact, date. And after briefly dating in 1999 we remained friends for years.
"I like Natalie, and I respect her intelligence and activism. But, to be honest, I can't figure out why she would actively misrepresent the truth about our (albeit brief) involvement. The story as laid out in my book Then It Fell Apart is accurate, with lots of corroborating photo evidence, etc.
"I completely respect Natalie's possible regret in dating me (to be fair, I would probably regret dating me, too), but it doesn't alter the actual facts of our brief romantic history."