We cannot say factually that Zimmerman gave up the chase
You are reaching. You can clearly hear the wind as he starts to run in the phone. That's why the dispatcher asked him if he was pursuing. He's also out of breath as he speaks. After he says ok, the wind noise dies down and his speech becomes more normal. If he was still running you would have known that.
Now you might assume that after he hung up with the dispatcher he continued the chase, as AliceinWonderland claims, but that would be only speculation on your part.
When the dispatcher asks the address of where he's parked, he says there's no address he's at a walk-through. So, if he's parked at the walk-through, got out to start the chase, got down the walkway to where Martin ran, then stopped running, it is conceivable that as he walked back to his car he was confronted by Martin as he claims, in the walkway where the altercation occurred.
Not saying this is what happened. It could have been as you say. But the solid evidence that we have so far fits my scenario.
You’re saying Zimmerman couldn’t stop, while talking to the operator, but resume the chase once he’s off the phone?