Frankie Grande was the subject of a scary situation on the streets of NY ... he got attacked and robbed by 2 teens.
NYPD sources tell TMZ ... Frankie was walking down an NYC street last week ... when he got punched in the back of the head -- the teens then jacked his bag and ran off.
A few hours after the attack, cops say a 17-year-old and 13-year-old attempted to use one of Frankie's credit cards at a nearby smoke shop.
Cops found out and beelined it for the shop, and swiftly arrested the 2. They were booked on assault, robbery, grand larceny and other crimes.
It's been a tough year for the Grandes ... TMZ broke the story, Frankie's sister, Ariana, avoided a dangerous situation earlier this year .after a man who'd previously been arrested for stalking her broke into her L.A. home back in June on her birthday.