100 Pound Girl Threatens To Annihilate Jerry Maguire Kid

Lipnicki filed a request for a restraining order against some 20-year-old actress named Amber Watson -- whom, we're told, Jonathan briefly dated after meeting in an L.A. acting class.

According to the documents, filed in L.A. County Superior Court, Lipnicki says he was asleep in his bed on May 14 ... when his roommates allowed Amber into the apartment and she immediately rushed into his bedroom.