The victim, 58, whom police did not identify, was walking near Roman Avenue and Brook Street at 4:40 a.m. when an unknown man pointed a black handgun at him and demanded money, police said.
The victim gave the man an undisclosed amount of cash before the armed man fled.
No one was injured.
The suspect was described as between 24 and 29 years old, 5 feet, 6 inches tall, with a medium build and wearing a blue shirt with white stripes and blue jeans.
Police ask anyone with information to contact Nassau County Crime Stoppers at 800-244-TIPS.