Correct, facebook harassment alone is not enough reason to call the cops, they will not care. It's when it goes beyond just facebook, to texting, calling, daily harassment on every form possible, openly talking about you in publoc scenarios, proved stalking, a true fear that can be rationalized of the person coming at you that you can call the cops. I've had that do that before and it is a very very long painful process that leaves a lot of mental scars. Blocking him on facebook seemed to work as far as my well being was concerned so there was no need yo take it any farther. My friends who were being stalked did call the cops however.