Erin, 38, was arrested in Walnut Creek after the altercation and booked for assault, police said.
But the actress told TMZ she attacked the man for "filming me without my knowledge in my private environment and I was defending myself."
"How much has he been filming me without my knowledge? The truth will come out," she said.
TMZ said attempts to reach the roommate for his side of the story have been unsuccessful.
The man has not yet been identified.
"The New Adventures of Pippi Longstocking" was released in 1988.