The girl sustained injuries on her face, lips and tongue and is admitted in a private hospital here, they said.
The accused, Jitendra Sakpal (21), who has done a hotel management course, was arrested on charge of attempt to murder yesterday.
According to Gorai police, Sakpal and the girl, both residents of suburban Dahisar, were in a relationship but parted ways a few months back after the girl's parents disapproved of their relationship. Sakpal had also proposed to marry her.
After repeated requests, the girl met Sakpal yesterday and the duo went to Gorai Jetty where an argument broke out.
The girl's father is a class IV employee in the city's civic body while the boy's father is employed with a private firm, police added.