The girl, Pooja, went missing while playing in Khajuwala area, last Friday.
Footmarks in the area suggest that she entered into Pakistan territory, police said.
"BSF authorities have contacted their counterpart in Pakistan and informed them about it.
They are in touch and efforts are on to trace her," district collector Arti Dogra said.
Pooja is a resident of 43 KYED area near the border, Additional SP Bikaner (Rural) Jainarayan Meena said.