It means you don't go out of your way to hunt those of different moral alignment/ethos of you.

If they attack you, defend yourself and kill them. You can chase them and kill them if necessary. Do not however, go around initiating the conflict.

You have to understand that this is within the context of the situation. If I see Joe Paladin sitting outside of the Village trying to take down Bob Duergar Warrior, I'm not going to smack Bob down.

If I see Bob Duergar warrior jumping on Joe Paladin at the Inn of the Eternal Star, I'm going to make a point to tell Bob to focus on why he is a Battlerager.