The 25-year-old German woman was struck by a stone that was thrown through the window of the taxi she was travelling in.
The incident happened around 11pm last night near the Broadway area in south Belfast.
The German woman and her two friends were travelling in the taxi when it is believed one of the young men, who were wearing hoodies, threw the stone.
It struck the woman in the face and she was taken to hospital with a broken jaw. The two other passengers and the taxi driver were unhurt.
Local community leaders and taxi drivers say this is an ongoing problem in the area that needs to be sorted out.
Anna Lo, Alliance MLA for South Belfast, described it was an appalling incident and warned that it could have resulted in a road accident if the driver had been struck.
