Ruffalo and Penn's brother Sean Penn were allegedly involved in an altercation with a photographer outside the Holy Cross Cemetery + Mortuary.
Ruffalo allegedly seized the photographer's video card out of his camera and refused to give it back.
The JUST LIKE HEAVEN star was the subject of a criminal complaint filed by the snapper after the funeral.
An official in the Culver City Police Department tells entertainment news website TMZ.com that his department has taken note that the photographer was on private property without permission.
No charges had been filed when Contactmusic.com went to press.