May I ask why you think that?
Because it was his neighborhood, he had a legal right to walk in it... it had been beset by burglaries and he was attempting to be proactive and help put an end to that. That's a noble and good goal.
He was trying to have the most up to date information of where the suspect was at when the responding officer called him back. Giving that officer an address on Twin Trees, which Trayvon was getting further and further away from... wasn't going to be much help.
Zimmerman was taking steps to try to actually bring about a confrontation. A confrontation between Trayvon and a police officer, that is. I don't believe Zimmerman ever desired to come into direct contact with Trayvon. I don't think he dreamed Trayvon would come back north. I don't think it was unreasonable for him to think he wouldn't.
It's unfortunate what ended up happening, but I don't think there was any way Zimmerman could have foreseen that outcome.
I can understand why Trayvon might have been alarmed that George had gotten out of his truck, but I think he had a lot of good options if he was scared, and most didn't even involve contact with George.
I think the proper way for that evening to conclude would have been George sheepishly realizing he'd gotten an officer out there for no reason, the officer never finding Trayvon, and Trayvon could've just told his dad about some guy who was tailing him.
But personally, I think Trayvon knew who George was on the phone with. I think he was sick of getting in trouble and acted on his frustrations. I think his goal was a one punch knockout, and he improvised very poorly when that didn't go to plan. That's just my speculation, though.