My sister falsely accused my brother of hitting her and called police?

My brother and sister were yelling at each other and she called police saying my brother hit her. When police arrived there were 2 other witnesses that told police it was all a lie. She was never even touched by the brother. The police said if the sister wants to press charges the brother will go to jail even though it was not true. Can the police take him to jail if there are witnesses stating it was a lie? This took place in Laguna Beach, CA.