It happened on Tuesday at 7:40 p.m. in East New York.
Police say the man followed the girl into the lobby of her building and attempted to sexually assault her before he ran away.
The victim was not injured.
The suspect is described as being a black man, 15-25 years old, 5'8", and 170 lbs. He was last seen wearing a dark jacket with light blue jeans and a black hat with a red emblem.
Anyone with information in regards to this incident is asked to call Crime Stoppers at 1-800-577-TIPS (8477).
You can also submit your tips by logging onto the Crime Stoppers website at WWW.NYPDCRIMESTOPPERS.COM or by texting your tips to 274637 (CRIMES) and then entering TIP577.