The 61-year-old recalled the incident in an interview to The Sunday Times Magazine, without naming the person involved. She said that looking back on the experience makes her "cringe", reports independent.co.uk.
The #MeToo movement prompted her to re-evaluate her past, she said.
"First, I thought, 'Well, I didn't experience that', but then as time went on I started going, 'Well, actually, there was that one time'," the actress said.
Explaining the "process" she went through, the star said she had denied the incident and blamed herself for it, having thoughts like "I shouldn't have worn that dress" or "I should've known".
"There were a number of situations that were not good. Like one incident -- I am not going to share -- but I look back and I cringe. I was really uncomfortable and it was inappropriate. I put it in a drawer. I was 20, and it was with a high-powered person in the industry," she said.
The actress added that if the man in question was still alive, she would write to him.
Pfeiffer's comments come after a spate of similar allegations from stars, including Naomie Harris and Sarah Jessica Parker, who revealed that she had reported a "big movie star" for "inappropriate behaviour" on set when she was a young actor.
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