Keri Claussen Khalighi told the Los Angeles Times in a story published Sunday that the incident happened in 1991, after she met Ratner and Simmons at a casting call in New York.
She claimed they took her to dinner and then back to Simmons' apartment to show her a music video. Khalighi said that is when Simmons allegedly began making aggressive sexual advances.
She said in the article Ratner "just sat there and watched."
In a statement, Simmons, now 60 years old, strongly disputed her account.
He said, in part: "As a long-time social activist, I have applauded the strength of the brave men and women who have spoken out over the past month and made their voices heard regarding sexual assault and harassment. I am a supporter of the #metoo campaign and the victims who were previously terrified to stand up and speak out against sexual misconduct. I completely and unequivocally deny the horrendous allegations of non-consensual sex against me with every fiber of my being."
There was no immediate comment from Ratner about the allegations