Rock created the popular sit-com "Everybody Hates Chris," and has starred in the films "I Think I Love My Wife," "Lethal Weapon 4" and "Dogma."
He was in court Friday to testify he hired Pellicano after a woman claimed she was pregnant with his child in 1999, the Los Angeles Times said.
DNA tests later proved Rock was not the father of Monika Zsibrita's baby.
The newspaper described the brash comedian's demeanor as uncharacteristically sober and soft spoken when he took the stand.
Rock was so quiet in his replies during his 15 minutes of testimony, U.S. District Judge Dale S. Fischer told him, "Project," so the court could hear him.
Prosecutors say Pellicano obtained unauthorized Department of Motor Vehicle and police information regarding Zsibrita after she asked Rock for money.
"Someone who was not pregnant with my child claimed to be pregnant with my child and requested large sums of money," Rock testified.
Pellicano is defending himself and declined to cross-examine Rock, the Times said.