The 69-year-old actress said he has nothing "good" to say about the veteran filmmaker, reported People magazine.
"I think he sexually assaulted a child and I don't think that's right. I have nothing good to say about him. I don't want to go there," Sarandon said.
The 80-year-old director became topic of discussion at the film festival after French comedian Laurent Lafitte made a joke at the premiere of his new film, "Cafe Society," that appeared to reference allegations that the Oscar winner sexually abused his stepdaughter Dylan Farrow.
Allen has denied the claim.
