"The fact that it's being brought up now is suspect, the timing is suspect. Nothing's happened, they haven't had any relationship for the last 20 years. So all of a sudden we're seeing these allegations surface again, and one has to wonder why," Elkan Abramowitz told NBC News in an interview.
"He is innocent," he said. "The case is over - there is no case."
Last week, Farrow's repeated her allegations in a letter published by The New York Times. She said Allen sexually assaulted her in the Connecticut house where she lived with her mother, Allen's then-girlfriend Mia Farrow.
Allen was never charged in the case.
Farrow's allegations come as Allen is being considered for an Academy Award for best original screenplay for his drama "Blue Jasmine", starring Cate Blanchett.
Connecticut prosecutors said this week there is no current investigation into the allegations.
Abramowitz, speaking on NBC's "Today" programme, said he does not believe that Dylan Farrow is lying.
Instead, he said, the idea that she was molested was planted by her mother and made her "a pawn in a huge fight" between Allen and his longtime girlfriend.
"I think she truly believes this happened," he said. "That memory is never going to go away."
Abramowitz said Allen's recent recognition in Hollywood prompted the renewed claims.
"It's a continuation of Mia Farrow's desire to hurt Woody Allen," he said, adding his recent lifetime achievement award at the Golden Globes "revived the anger she has toward him".
He added Allen "is not interested in suing anybody for defamation."