George Zimmerman -- Questioned by Cops in Alleged Road Rage Incident

George Zimmerman allegedly threatened to kill a man in Florida earlier this week during a road rage incident ... and cops pulled over Zimmerman to grill him about it.

According to the Lake Mary PD, a man named Matthew Apperson called 911 on September 9 and told the operator Zimmerman had pulled up next to him and began yelling, "Why are you pointing your finger at me? I'll f***ing kill you. Do you know who I am?"

Apperson says he drove away to a store where Zimmerman followed him to continue the verbal barrage. Apperson called 911 from inside the store, but according to cops ... Zimmerman was gone when they arrived.

Apperson claims 2 days later, he saw Zimmerman parked outside his work, and called police again. Cops responded and pulled Zimmerman over near the office. After questioning him, police decided not to press charges -- mainly because there was no independent witness.

For what it's worth ... Apperson is white. Also, he was carrying a gun at the time of the alleged run-in, but he has a permit for it.