"I was scared for my life and my daughter's," she told People magazine in a story published Wednesday. "I thought he would kill me."
She also told the magazine that she did not leak the tapes purportedly of Gibson in a series of racist and misogynistic rants.
The recordings were made a month after the alleged physical abuse.
The actor's representatives declined to comment on Grigorieva's interview and did not participate in the People story.
The alleged abuse was not reported to authorities until months later, after the couple broke up and became embroiled in a custody dispute over their daughter. An investigation into Grigorieva's domestic violence claims has been completed by the Los Angeles County Sheriff's Department. The results have been turned over to prosecutors.
The Associated Press contributed to this report.