Rhys Ifans will not be charged in relation to an incident at the Comic-Con festival on July 22.
After reviewing differing witness accounts, our prosecutors concluded there was not sufficient evidence to prove the case beyond a reasonable doubt.
The Welsh actor was accused of pushing a female guard while at the event in California to promote his new movie 'The Amazing Spider-Man', but insufficient evidence means Rhys - who reportedly smelled of alcohol when he was arrested - will not face prosecution.
Gina Coburn, a spokeswoman for the San Diego Office of the City Attorney, said: "After reviewing differing witness accounts, our prosecutors concluded there was not sufficient evidence to prove the case beyond a reasonable doubt."
Rhys allegedly became angry when his friend was refused admission to the event, and he was accused of pushing the guard to try and get through, leading to her making a citizen's arrest.
Lieutenant Andra Brown from the San Diego Police said at the time the blonde star was "berating" a number of things including the United States.
She said: "He was aggressive and belligerent. He was berating everyone from the security staff to the United States of America. He was cited and released, which is a non-custodial misdemeanour arrest."