When different enemies respond differently--ie. some chase you and some don't that is actually a nice touch and makes the game more interesting imo. If certain enemies are unrelenting in their pursuit that simply makes the game more of a challenge. If you can't handle one of these enemies then teleport out and go back later when you are a higher lvl.

The question is not, Can they reason? nor, Can they talk? but, Can they suffer?
~Jeremy Bentham