In an interview with The Telegraph, Mr Dershowitz said it was more difficult for the Duke to take the kind of action he is pursuing in the media and through the courts. "He's a royal and it's much harder for a royal to get down into the dirt the way I'm able to do," he said.
Mr Dershowitz also said he was in a "somewhat different situation" to the Duke because he claims to have never met Ms Roberts, while a photograph shows Prince Andrew with his arm around her, proving that they had at least met.
Prince Andrew with his accuser, Virginia Roberts. Photo / Supplied
"I know I didn't do it. He should only come out and make statements if he can do it with the same kind of certainty that I can do it," Mr Dershowitz said.
"Remember: there's no photograph of me with her, there's no diary of me that she wrote about. he's in a somewhat different situation. He apparently did meet her, I never did."
In a lengthy affidavit filed in a Florida court, Ms Roberts said she had sex with Mr Dershowitz "at least six times" beginning when she was an underage 16-year-old. In the same file she claims to have had sex with the Duke three times, including as part of an 11-person "orgy" on a Caribbean island.
Mr Dershowitz said he had not been in contact with the prince or his lawyers about the allegations and that he had not spoken to the Duke in a decade.
The two men were first introduced through Jeffrey Epstein, a millionaire financier who in 2008 pleaded guilty to soliciting sex from underage girls. Mr Dershowitz helped negotiate Epstein's plea bargain, which saw the sex offender serve just over a year of an 18-month sentence.
Ms Roberts, who claims Epstein kept her as "a sex slave", is trying along with several other women to sue the US government on the grounds that the plea bargain was too lenient.
Mr Dershowitz said he had met the Duke several times, both on his own and with Epstein, but had never seen the prince with Ms Roberts or in any compromising position with women or girls.
While he could not say the Duke was definitely innocent of the allegations, he said "no one should believe anything that Virginia Roberts says, she's proven her lack of credibility over and over again."
Mr Dershowitz said he and the Duke had debated Middle East politics at a dinner at the British consulate in Boston. "I liked him. He's an intelligent, inquisitive guy," the professor said.
Ms Roberts is protected from a defamation lawsuit because she made her allegations in official court filings, but Mr Dershowitz said he intended to sue her if she repeats the claim in the media.
He added that he was trying to locate Ms Roberts to serve her with court papers as part of the defamation suit her lawyers have launched against him.
"We'll find her. We're going to find her, we know where she is, she can't hide from us."