Iraqi Prime Minister Nuri al-Maliki has called on residents of Fallujah to take action to expel Al-Qaeda-linked militants from the city and avert an assault by the country's army.
In a statement broadcast on state-run television on January 6, Maliki denounced the militants as "terrorists."
He warned that Fallujah could face the "danger of armed clashes" if the military moves in.
Maliki added that he had ordered security forces not to attack in residential areas.
The statement comes amid reports that the Iraqi government is preparing a major assault to repel the Sunni militants and retake control in Anbar Province.
Fighters of the Al-Qaeda-linked Islamic State in Iraq and the Levant last week seized parts of Fallujah and the nearby capital of Anbar Province, Ramadi, in what has been seen as a serious challenge to Maliki's Shi'ite-led government.
Scores of people have been reported killed in fighting in Anbar in recent days, and reports have spoken of thousands of residents fleeing the violence.
Observers say the militant offensive marks the first time in years that Sunni insurgents have seized and held territory in major cities in Anbar, a vast western province that shares borders with Syria, Jordan, and Saudi Arabia.
Secretary of State John Kerry has pledged U.S. help to oust the militants, but said there were no plans to send American troops to the battle.
"We are going to do everything that is possible to help them, and I will not go into the details except to say that we're in contact with tribal leaders from Anbar Province whom we know are showing great courage in standing up against this as they reject terrorist groups from their cities," Kerry told reporters on January 5. "And this is a fight that belongs to the Iraqis."
The region, west of Baghdad, was the site of major U.S. operations against militants following the 2003 invasion that toppled Iraqi ruler Saddam Hussein.
After several years of fighting, American troops, supported by Sunni Arab tribesmen, were able to take back control of Anbar from militants.
U.S. troops withdrew from Iraq in December 2011.
Iran, an ally of Maliki's government, has also offered assistance.
In Iran, the state-run Islamic Republic News Agency (IRNA) quoted the deputy chief of staff of Iran’s military, General Mohammad Hejazi, as offering "equipment and advice" to help in the fight against the militants.
However, the general said there had been no request from Baghdad for a joint operation. He added that Iraq’s military is not facing a shortage of manpower.
The latest fighting broke out in Anbar Province on December 30 after a Sunni protest camp in Ramadi was dismantled by government forces.
The government had accused the camp of serving as a base for Al-Qaeda-linked militants.
Iraq’s Sunni minority has for years accused the Shi'ite-led government of seeking to marginalize their community.
Meanwhile, in related news, Iran says it is ready to help Iraq in its ongoing battle against Al-Qaeda.
The deputy chief of staff of Iran's army, General Mohammad Hejazi, was quoted by Iranian media on January 6 as saying that Iran can offer "military equipment and advisers" should Baghdad ask for them.
He ruled out sending troops to Iraq, however, and also noted that “nothing has been discussed."
With reporting by AP, AFP, dpa, and presstv.ir