The incident took place on July 4 at Chimbipada in Bhiwandi here when the girl was alone at her home. The accused was arrested yesterday.
According to police, the accused came to the house asking for the girl's parents. When he came to know that they had gone out, he asked her to bring him some water. As she went inside to fetch water, the accused molested her.
The man then threatened the girl and asked her not to reveal anything to anyone, they said.
The accused was booked under section 354 (assault or criminal force against woman with intent to outrage her modesty) of the IPC and various sections of SC/ST (prevention of atrocities) Act, besides section 8 of the POCSO (Protection of Children from Sexual Offences) Act, police said.