Jaafari faced widespread criticism for being ineffective and controlling during his 10-month tenure as the country's top executive.
He acknowledged his previous administration's weaknesses and vowed to listen to those outside his political circle in forming a government.
"Any failure or frustration about a minister will be reflected on the government as a whole," he told reporters.
"Any party in the government has the right and duty to discuss candidates. No doubt, we will consider all the different parties which form the parliament."
Jaafari did not spell out any major proposed changes for his administration but said he would tighten the screws on ministers, who he suggested had been spending too much time out of the country.
"The manner of work, the pace, the centralization of the government ... all will witness a qualitative leap," he said.
Jaafari, a 58-year-old physician and theologian who has been active in Islamic politics for four decades, faces daunting challenges.
Skeptical political blocs already are allying against him.
Followers of Shiite cleric Muqtada Sadr within his own coalition demand more radical measures from the government.
The coalition made him its choice for prime minister by a single vote in an election Sunday.
His work will proceed amid continuing sectarian violence that claimed at least 11 lives Tuesday in the Shiite city of Balad, where gunmen attacked a group of farmers. Several large roadside bombs rocked the capital, injuring half a dozen Iraqis.
Jaafari said that improving the country's dire security circumstances will be his top priority.
But many Iraqis and Western officials regard his government as part of the problem.
Another faction in his coalition, followers of Shiite cleric Abdul Aziz Hakim, has control of the Interior Ministry, which members of the Sunni minority accuse of spawning death squads.
The Shiite coalition, which controls 130 of the 275 seats in parliament, cannot form a government without a two-thirds majority of lawmakers and needs to build a coalition with Kurds, secular Iraqis or Sunni Arabs.
Iraq's Kurdish leaders opposed Jaafari and have complicated his task of assembling a government.
They say Jaafari didn't grant President Jalal Talabani, a Kurd, more than a ceremonial role and failed to invoke a constitutional article calling for the return of dispossessed Kurds to the oil-rich city of Kirkuk.
Jaafari said he felt sympathy for the displaced Kurds but urged patience.
"We have a constitution and a law," he said. "My success, values and morals aren't based on my feelings but on how well I can apply the constitution and the law."
Now Kurds say they won't form a government without the participation of the Iraqi List, the coalition of former Prime Minister Iyad Allawi, a secular Shiite.
"We think that it's important not to exclude anybody," Talabani said at a news appearance Tuesday with Hakim.
"We believe the Iraqi List has struggled against Saddam Hussein and includes many individuals who struggled against the tyrant regime," he said.
Sunni Arabs, with about 55 seats in the parliament, and Allawi's followers have allied to form a bloc with the goal of preventing Shiites and Kurds from remaking Iraq as a country divided into separate federal regions.
Their alliance could complicate efforts by Jaafari to draw at least some Sunnis into any ruling coalition.
HOSTILITIES IN BASRA: Authorities in the southern Iraqi province of Basra severed all ties with Britain amid the furor over alleged British military abuse of several Iraqi males two years ago in Amarah, 180 miles southeast of Baghdad.
British military officials called the Basra decision regrettable. The provincial police chief said all security cooperation and joint patrols with British soldiers were called off throughout the vast southern province.
"Decisions like these and reductions in patrols hinder the process of promoting security and economic reform and merely work to the detriment of the people of Basra," British military spokesman Capt. James St. John-Price said.
Basra authorities also demanded the 530-member Danish military contingent leave unless the Danish government apologizes for the contentious Prophet Muhammad drawings that appeared in Danish and European newspapers.
GUNMEN KILL 11 SHIITE FARMERS: Gunmen attacked a group of Shiite farmers in Balad, 50 miles north of Baghdad, shortly before midday Tuesday, police chief Brig. Mohammed Baldawi said. Sheik Hussein Hayali, owner of the farm, and seven other members of his family were killed, Baldawi said.
COALITION SOLDIER SLAIN: Two attacks in Baghdad on Tuesday killed one coalition soldier and wounded six others, the U.S. military said. The military press office said it did not know the nationality of the victims.
Sgt. Stan Lavery said a roadside bomb targeted a military vehicle at 10:30 a.m. in Abu Ghraib, western Baghdad, killing one soldier and wounding two others.
About an hour later, another coalition convoy was attacked in Baghdad's western Salaam area, wounding four soldiers.
-- Times wire services