Screenwriter Joe Eszterhas claimed in his nine-page letter that Gibson used racist, offensive and sexist language, even threatening to kill ex-girlfriend Oksana Grigorieva.
Both Eszterhas and Gibson worked on the script to The Maccabees, about a Jewish revolt, until the project fell through.
"Everybody is looking to make Mel look bad," Rourke told TMZ. "He's an easy f**king target."
"We live in a town that's built on envy. What do you expect?" he added.
Rourke was last seen in 2011's Immortals, but he is set to appear as a terrorist on the thriller Java Heat.
Watch the trailer for Immortals below: