The robbery was reported shortly before 8:30 p.m. Tuesday near the intersection of Seventh and Stevenson streets, according to police.
A white man in his 30s driving a dark Volvo SUV stopped it at the intersection and called out to the 34-year-old victim, requesting that he walk over to the car, police said.
The suspect told the victim that he was a "narc" officer and requested the man's wallet. When the victim complied, the suspect took the money out of the wallet and fled in the SUV, police said.
The victim was uninjured in the robbery.
No arrests have been made in the case, according to police.