Unfortunately, getting pushed is not harassment, neither is a plethora of other actions far worse than that.
Someone sneaks up behind you while you are naked and afk in town, and tries to bash your head in with a two-handed sledgehammer.
You are about to start mining just outside of guard range when someone comes along and thunderlashes you to death.
You are heading to the graveyard when a murderer comes out of nowhere and kills you.
And thievery hasn't even been implemented yet.
Welcome to Mortal Online 2.
What you can do instead, is back yourself to a wall in a corner so no one can push you. Or arm yourself to the teeth, surround yourself with badass pvpers who like you, and start pushing back.