Khanna SHO Jagdish Raj said a case has been registered against the man under various sections of IPC, including rape, based on the statement of the victim's mother.
The victim's mother told police her 6-year-old daughter was playing outside on Tuesday when the suspect offered her toffee.
He then took the girl inside his house and sexually assaulted her, police said.
Deputy Inspector General of Police (DIG) Y S Hayer said the suspect would be subjected to a medical examination to ascertain whether he was capable of committing the crime.