Unfortunately, you've just learned that "playing around" in the workplace can have consequences. You may have thought that you were just playing around but she evidently did not agree. She has the right under the law to report what she perceives as an assault, even if you did not intend it that way. The termination was legal; if she was able to perceive it as an assault (intended or not) then it was inappropriate for the workplace to begin with. As for a police record, well, maybe if you're lucky law enforcement will decide not to pursue it, but you haven't told us enough to us to guess whether that's likely or not.