Police Sgt. Gary Knight said none of the owners of property on which the posters were placed wanted to press charges against Alba, who has apologized.
Police never interviewed the 28-year-old co-star of the "Fantastic Four" movies, "Sin City and "Good Luck Chuck." She is in Oklahoma City shooting a movie, "The Killer Inside Me."
Police found the posters - aimed at raising awareness about sharks' declining numbers - glued to a downtown bridge, utility boxes and a billboard for the United Way charity.
Knight said it is typical not to pursue vandalism charges when property owners don't want to prosecute.
Copyright 2009 The Associated Press.