The collision happened as the child was crossing in Harewood Street at around 5.25pm on Sunday, September 9.
A West Yorkshire Police spokesman today said: "The child suffered a serious but not life-threatening leg injury.
"The driver of the vehicle stopped at the scene and offered to provide his details but the child’s father said they were not required."
Officers now want to speak to the driver or any witnesses to the collision.
Contact police on 101, quoting 13180453338, or use the live chat facility on the forces website.