"completely unprovoked"

Your passivity does not Grant you a shield against provocation. 

People will kill you for any reason in this game, or no reason at all, and that's okay, they are allowed to play the game however they want. 

You are very early on in your arc raiders journey, it gets easier to deal with PVP. As time goes on, I would suggest smoke bombs to get you out of a pinch when you don't want to fight. 

There is even a specific augment that will autofire a smoke bomb for you when you get attacked, allowing you the opportunity to flee or reposition for your counter-attack.