When I was a teenager my town had something called "react" they were volunteers from the community and they drove around and reported suspicious activity to the police. Me and my friends were often followed by these do-gooders, and it always pissed us off pretty bad. Sure we were all bad kids, and were in fact up to no good, but these guys were not cops and had no right to follow us around and spy on us. One time one of them got out and started following us and eventually chasing us through back yards. We all decided if he caught up to us, we were going to kick the crap out of him. He never caught up to us and we didn't beat his ass, but it was that close.
Looking back on the situation, sure the guy was wrong for chasing us, he must have thought we did something wrong, still don't know, but we would also have been in the wrong by making the confrontation physical and punching him. I live a town that doesn't allow handguns, but if we'd attacked him, you never know what will happen from there.
Also, If Zimmerman was arrested for assaulting a police officer I'm surprised he is able to have a conceal carry permit. Can you own a firearm in Florida if you have a felony?