The 26-year-old American actor told The Associated Press he was "done" with the action-packed franchise, adding he "doesn't have anything new to contribute."
Speaking at the recent opening of "Transformers: Dark of the Moon" at the Moscow International Film Festival, LaBeouf said he did not know if "there's anywhere to take Sam, really."
Directed by Michael Bay, "Transformers 3" also stars Patrick Dempsey, Frances McDormand, John Malkovich and Victoria's Secret model Rosie Huntington-Whitely.
Paramount Pictures said the movie earned $37.3 million Wednesday in the U.S. on its first day - a 40 percent drop from its predecessor, "Revenge of the Fallen."
