The 46-year-old movie star took several open-hand slaps to the face on the red carpet at the 350 Days premiere in Hollywood on Thursday ... when he was ambushed by pro wrestler RJ City.

The two -- who happen to be facing off at a wrestling match on July 15 -- started jawing at each other on the red carpet ... but things turned physical and RJ let them hands fly!

The "fight" was quickly broken up and City was escorted off the carpet.

Afterward, Arquette told us he's been training his ass off to demolish City on Sunday -- even traveling to Tijuana, Mexico to train with luchadores.