The pact, signed on Saturday, read: "Realising the gravity of the situation our country is undergoing, we pledge in front of God and the Iraqi people to be sincere and serious in preserving the unity of our country."
The chiefs also pledged to "work hard to stop the bloodletting and ... sectarian killings that have nothing to do with our values". A representative read out the agreement, which he described as a "pact of honour" on live television.
Nour Al-Maliki, the Iraqi prime minister, and his fellow Shias say that amnesty can be given to anti-government fighters who have not killed any Iraqi.
But given the widespread killings, it would be hard to find a fighter who does not have blood on his hands. Differences among Shias themselves is another hurdle.
There is also the question of how to deal with fighters from the minority Sunni Arab community who hope to regain the power they held in the sunni-dominated regime of Saddam Hussein.
"These tribes have to play a significant role in fighting terrorists, saboteurs and infiltrators"
Iraqi Prime Minister
In an opening speech at the chiefs' conference, Al-Maliki said: "These tribes have to play a significant role in fighting terrorists, saboteurs and infiltrators."
Although the pact is unlikely to bring peace to Iraq, it is an important step towards winning support in this divided nation for al-Maliki's 24-point reconciliation plan that was unveiled last month.
None of the major Sunni Arab armed groups has publicly agreed to join the plan, and many of the Shia militias are controlled by legislators themselves.
In other news, lawmaker Tayseer al-Mashhadani was released on Saturday, nearly two months after she was abducted on July 1, Yassin Majeed, an adviser to the prime minister said.
No group claimed responsibility for the kidnapping of al-Mashhadani, a Sunni. But it appeared to confirm suspicion that she was held by a Shia militia in an attempt to stoke sectarian tensions.
Violence continued around the country on Saturday when a roadside bomb exploded in a soccer field during a match in Balad Ruz near Baquba, killing four people and wounding 20.
The violence in Iraq has left a
psychological scar on its people
Armed men shot dead the Shia owner of a bakery and a policeman in separate incidents in western Baghdad.
In other areas, roadside bombs and clashes with security forces killed 16 people on Saturday.