(CNN) -- Prime Minister Nuri al-Maliki is calling on political parties to unite against armed groups in Iraq, a spokesman said Sunday, warning that "Iraq cannot be the new Somalia."
"It is a clear message," al-Maliki spokesman Ali al-Dabbagh said of the situation in Iraq. "We cannot accept the presence of armed groups."
Somalia has been mired in chaos since 1991, when warlords overthrew dictator Mohamed Siad Barre and then turned on each other.
Earlier in the day, a lawmaker and member of Shiite cleric Muqtada al-Sadr's political bloc issued an ultimatum demanding al-Maliki's government immediately end its attacks on Shiite militias or "all options are open to us."
The Sadrist lawmaker Fawzi Tarzi also condemned the government's call to disband al-Sadr's Mehdi Army, saying that the demand "will mean the end of al-Maliki's government."
"And therefore the siege of Sadr City and Shula should end immediately or all options are open to us," Tarzi said. "There is a fierce military and media campaign and a dirty political conspiracy planned and supported by the occupier against the Sadr trend."
Sadr City has been the scene of many clashes in recent weeks between U.S. and Iraqi Security Forces and the Mehdi Army.
Tarzi made his remarks as U.S. Secretary of State Condoleezza Rice made an unannounced visit to Baghdad.
During Sunday remarks, Rice praised the Iraqi military for its recent operations targeting Shiite militants in Basra, an al-Sadr stronghold, saying it "fought very bravely in this recent operation."
She added that al-Maliki's government has shown it "will take on any group in their country, no matter what sect, that challenges the rule of law and the legitimate authority of the national government."
Tarzi's comments also follow airstrikes and firefights Saturday that left seven Shiite militants dead in Baghdad's Sadr City.
Sadr City has been the scene of many clashes in recent weeks between U.S. and Iraqi security forces and the Mehdi Army.
Tarzi called on humanitarian organizations and the world media to visit Sadr City to see what he described as a "humanitarian tragedy."
The Baghdad neighborhood is plagued with "random airstrikes and raids," which are causing a deteriorating humanitarian situation, he said.
More than 400 people have died and 1,300 have been wounded in the attacks, Tarzi said, citing hospital figures.
Al-Sadr on Saturday gave his "last warning" to the Iraqi government that he would "declare a war" unless U.S. and Iraqi forces stop their assaults on his followers.
Loudspeakers at Sadr City mosques announced al-Sadr's warning Saturday evening, calling for followers to fight the "occupier," a witness said.
According to the Interior Ministry, Saturday's Sadr City clashes killed nine Iraqis and wounded 15 others.
The Interior Ministry said Sadr City clashes continued into Sunday morning.
Al-Sadr's threat was issued the same day that a man claiming to be the leader of al Qaeda in Iraq urged his fighters to launch an offensive against U.S. forces in the next few weeks.
The speaker was identified as Abu Hamza al-Muhajir, also known as Abu Ayyub al-Masri, on several Islamist Web sites that posted the recording.
Within the the next month, militants should "offer the head of an American as a gift to the deceitful [President] Bush," he said.
The speaker also called for attacks on members of Iraqi awakening councils, a movement of mostly Sunnis who have joined forces with the U.S. and Iraqi governments in battling Islamic jihadists loyal to al Qaeda in Iraq.
The U.S. military shut down the International Zone on Sunday after U.S. officials announced Rice's arrival. Rice met with Iraqi leaders and U.S. officials in the heavily fortified district that houses U.S. and Iraqi governmental offices.
In addition to applauding military operations, Rice also congratulated al-Maliki on recent political accomplishments, namely an oil and gas law that the prime minister's office say will be completed soon.
"It is indeed a moment of opportunity in Iraq thanks to the courageous decisions taken by the prime minister and a unified Iraqi leadership," Rice said Sunday.
The military said it was shutting down the International Zone during Rice's visit for "force protection purposes."
Witnesses said they saw vehicles being turned away from checkpoints near the zone.
Rice is scheduled to be in Kuwait on Tuesday's for the Iraqi neighbors conference.
She said she hopes the conference will "reinforce the really significant progress that Iraq has made since our meeting last November in Istanbul."
The first neighbors' conference in Sharm el-Sheikh, Egypt, in May addressed Arab concerns about the al-Maliki government and its inability to foster political reconciliation among Sunni, Shiite and Kurdish factions.
The second conference in November in Istanbul, Turkey, was largely overshadowed by an increase in fighting between Turkish forces and Kurdish rebels based in northern Iraq.