Families who could not leave should raise white flags to mark their location in the city just west of Baghdad, Reuters quoted the TV channel as saying.
Falluja was the first Iraqi city to fall to Daesh (ISIL or ISIS) terrorist group in January 2014, six months before the group swept through large parts of Iraq and neighboring Syria.
The army "is asking the citizens that are still in Falluja to be prepared to leave the city through secured routes that will be announced later," the channel said.
The city on the Euphrates River 50 km (32 miles) west of the capital, had a pre-war population of around 300,000.
It is encircled by Iraqi forces and a coalition of voluntary forces known as Hashid Shaabi.
Known as the "City of Minarets and Mother of Mosques", Falluja was badly damaged in two offensives by US forces against al-Qaeda insurgents in 2004.