Zimmerman followed Martin. With a gun.
Here's part of the Wikipedia account.
“About two minutes into the call, Zimmerman said, “he's running”.[51] The dispatcher asked, “He's running? Which way is he running?”[52] Noises on the tape at this point have been interpreted by some media outlets as the sound of a car door chime, possibly indicating Zimmerman opened his car door.[53] Zimmerman followed Martin, eventually losing sight of him.[51] The dispatcher asked Zimmerman if he was following him. When Zimmerman answered, “yeah”, the dispatcher said, “We don't need you to do that.” Zimmerman responded, “Okay.”[54] Zimmerman asked that police call him upon their arrival so he could provide his location.[51] Zimmerman ended the call at 7:15 p.m.
After Zimmerman ended his call with police, a violent encounter took place between him and Martin. It ended with Zimmerman fatally shooting Martin 70 yards (65 m) from the rear door of the townhouse where Martin was staying.”
Zimmerman did not attack Martin. Martin came out of the dark and attacked Zimmerman. Zimmerman didn’t even know where Martin was - not exactly - until Martin initiated contact.
“After a discussion about where Zimmerman would meet police, the call ended, and Zimmerman told investigators he was returning to his vehicle after locating an address on Retreat View Circle when Martin approached him from his left rear and confronted him.” - Wiki
Zimmerman didn’t have a shotgun out as he pursued. Zimmerman was trying to WATCH while in contact with the dispatcher. And Martin initiated contact. VERY different, eh?
Grow up!