Safe zone from enemies.

Hi guys,

the problem is the following:

My main character moves around the map, and when enemies are closer to him, they chase him, however I want to have a sort of "safe zone", in my case, a river in my map.

Is there anyway I could to to prevent them from coming into that zone, so they stop just in front of it?

It would be like a solid, which is only solid for some objects, so they collide, and can't move through it.

I've tried to create a sprite, and when an enemy collides with this sprite, they stop following me, but then, when I'm out of my safe zone, they won't chase me any more.

Okay, nevermind, I already solved it.

I have a player variable, which tells me if I'm on earth or in water.

I set the enemies to chase me just when I'm on earth.