During a chat with Yahoo CEO Marissa Mayers, Lawrence criticized "shows like Fashion Police" for teacher young people it's okay to be bullies.
"There are shows like the Fashion Police that are just showing these generations of young people to judge people based on all the wrong values and that it's OK to point at people and call them ugly or fat," she said. "We have to stop treating each other like that and stop calling each other fat."
The 80-year-old comedian, who isn't known for holding back, took to Twitter to slam Lawrence's comments.
"It’s funny how Jennifer Lawrence loved @E_FashionPolice during Awards Season when we were complimenting her every single week," Rivers tweeted last week. "But now that she has a movie to promote, suddenly we’re picking on all those poor, helpless actors."
"WAIT! It just dawned on me why Jennifer Lawrence fell on her way up to the stage to get her Oscar. She tripped over her own arrogance," Rivers' added in reference to Lawrence's onstage slip earlier this year.