The body was recovered near Thathera Colony on Pataudi Road, they said adding the girl was kidnapped yesterday.
Police said they were also looking into the possibility of the kidnapper sexually assaulting the girl.
"There is a possibility of the kidnapper sexually assaulting the girl before strangulating her," a police official said.
A case of abduction and murder had been registered by the Rewari Sadar Police, he said.