Al-Janabi stated this in a two-page document addressed to Muslims across the world, dated 5 December.
"Your brothers on the Falluja Council of the Mujahidin and those from other factions stand committed before God and before you to continue the Jihad against the occupiers and their agents until they leave Iraq."
They "would continue whatever the sacrifices", he said.
"We defy [US President George] Bush, to reveal to his people, his failures in Falluja, which has become the symbol and the voice of all oppression in the world and a solid platform of the resistance in Iraq."
The Falluja campaign was the start of a "Zionist crusade spearheaded by the crusader, the cursed Bush, and [Iraqi interim Prime Minister Iyad] Allawi to wound our civilisation, doctor our religion and falsify our Quran".
The US will use fingerprints and
Iris scans to track Falluja residents
In another statement, al-Janabi - who is believed to have fled the city - congratulated Falluja residents for their "resistance".
Their sufferings were "divine ordeal", he said, calling the offensive "a war between crusaders and Zionists" against a "symbol of Islam and Muslims".
Meanwhile, a top US commander in Iraq on Thursday said fingerprint and iris scans would be used to track civilians returning to Falluja.
The scans are one of several measures US-led forces are putting in place amid fears that fighters hiding among the tens of thousands of refugees expected to return to the battered city in coming weeks will renew their fight against US and Iraqi troops.
"When people start to return, military-aged men will be entered into a biometric [system]. Their fingerprint and iris scans will be taken and they will be given an ID card," Sattler said.
"We're doing this to establish a database."
"We are very reluctant to say that we have broken their backs. We have given them a very strong jolt and disrupted their operations"
Major Jim West,
senior US intelligence officer
Suspected fighters captured in the aftermath of the massive US-led assault on Falluja have all been similarly scanned.
But this will be the first time the system is used on civilians in Iraq, said Major Francis Piccoli, spokesman for the 1st Marine Expeditionary Force, who acknowledged there has been some opposition to the measure.
In Baghdad, a senior US intelligence officer on Thursday said the offensive on Falluja had hurt but not broken Iraq's fighters and violence would go on even if Iraq holds successful elections.
"We are very reluctant to say that we have broken their backs. We have given them a very strong jolt and disrupted their operations," said Major Jim West.