Matthew Fox -- No Criminal Charges for Alleged Party Bus Fight

"Lost" actor Matthew Fox will not be prosecuted for allegedly punching a female party bus driver in the breast and vagina during an alleged altercation last month ... TMZ has learned.

A rep for the local Cleveland Prosecutor's Office tells TMZ, "There will be no charges brought. After a review of the facts [officials] came to the conclusion not to charge."

As TMZ previously reported, the party bus driver has already filed a lawsuit against Fox -- claiming the actor was drunk and tried to force his way onto her bus ... when he attacked.

The woman claims she injured her hand trying to fight him off ... and now she wants more than $25k in damages.