Stones were thrown at the boys and girls as they left the Forthspring Centre on the Springfield Road, at around 8.15pm on Wednesday.
North Belfast MLA William Humphrey said some of the group were hit on the back as they fled through an alleyway.
"These Protestant teenagers were leaving the Forthspring Centre after attending a meeting," the DUP representative said.
"They were effectively ambushed by a group of around 10 nationalist youths who were waiting for them to emerge and who threw rocks and bottles at them and shouted sectarian abuse.
"At least one girl was hit on the back with a rock. These Protestant youths had to get away via a rear alleyway as the interface gate at Workman Avenue. The young people were terrified by the ordeal and were left very badly shaken."
Police said they are following a definite line of inquiry and asked anyone who was in the area at the time or who witnessed the incident to come forward.
A statement said: "Police in Grosvenor Road are appealing for information following the report of a sectarian attack in the Springfield Road area on Wednesday.
"It was reported that at around 8.15pm a group of teenagers were attacked by a group of youths throwing stones. There were no reports of any injuries.
"Police are following a definite line of enquiry and would ask anyone who witnessed this incident to contact them at Grosvenor Road on 0845 600 8000."