Law enforcement sources tell TMZ, Furlong flagged an officer making the rounds in Skid Row -- one of the most drug-infested area in L.A. -- and claimed he had asked a man for directions ... and the man aggressively demanded his wallet.
Not wanting trouble, Furlong says he obliged ... and the dude took off. No weapons were used.
But here's the thing ... walking around asking for directions in Skid Row -- which contains one of the largest homeless populations in the U.S. and is renowned for its drug dealing -- isn't the brightest idea. Especially at odd hours during the day.
(It's also suspicious -- but that's beside the point.)
We're told Furlong filed an incident report with the police, and a robbery investigation is currently underway.