In a televised address, Nuri al-Maliki also thanked the international community for its support in the fight against al Qaeda and urged the group's members and supporters to surrender, promising clemency for those who did.
America said earlier this week it would fast-track deliveries of military hardware, including drones and missiles, to Iraq, but ruled out sending troops two years after Washington ended nearly a decade of occupation.
Mr Maliki said: "The support is giving us the confidence we are moving on the right course and that the result will be clear and decisive: uprooting this corrupted organisation.
"We will continue this fight because we believe al Qaeda and its allies represent evil."
Fighters from the al Qaeda affiliated Islamic State of Iraq and the Levant (ISIL), which is also active across the border in Syria, overran police stations in Fallujah and another city in Iraq's western Anbar province last week.
The army deployed more tanks and artillery around Fallujah on Tuesday as local leaders tried to persuade militants to leave in order to avert an impending offensive that has echoes of American assaults on the same city in 2004.