The incident took place on Friday and the matter was reported to police by the parents of the girl yesterday.
Police said the girl was playing outside her house when the accused lured her and allegedly sexually assaulted her.
The girl is the daughter of a Nepali couple working as labourers and the accused is son of the landlord.
A case under the Protection of Children from Sexual Offences (POCSO) Act was registered after a complaint was filed by the parents of the child.