Almost 1,000 people were killed and more than 2,000 wounded in violence in Iraq in September, the UN has said.
Baghdad was the worst affected province as 887 civilians and 92 members of the Iraqi Security Forces died nationwide.
The death toll was lower than July's, which stood at 1,057, but still one of the highest in years. It brings the number killed this year to 5,740.
The UN's envoy urged Iraqis to "strengthen their efforts to promote national dialogue and reconciliation".
"Political, religious and civil leaders as well as the security services must work together to end the bloodshed and ensure that all Iraqi citizens feel equally protected," Nickolay Mladenov said in a statement on Tuesday.
Most of the violence has been blamed on Sunni Islamist militants linked to al-Qaeda in Iraq (AQI), which has said it was behind the series of car bomb attacks in predominantly Shia districts of Baghdad on Monday that left more than 54 people dead.
A statement posted online by the Islamic State in Iraq and the Levant (ISIS), an umbrella group to which AQI belongs, said the bombings were revenge for a "campaign of torture, displacement, detainment and liquidation" of the Sunni minority by the Shia-led government.
On Wednesday, at least four members of the security forces were killed when an Iraqi military helicopter was shot down during an operation against militants in a desert area west of Baji, north of the capital, officials said.
The recent unrest was sparked by an army raid on a Sunni Arab anti-government protest camp near Hawija in April. The protesters were calling for the resignation of Shia Prime Minister Nouri Maliki and denouncing the authorities for allegedly targeting the minority Sunni community.
Iraq has also seen a spill-over of violence from the conflict in Syria, where jihadist rebels linked to the Islamic State of Iraq, a Sunni militant umbrella group that includes al-Qaeda, have risen to prominence.
In the past two months, Iraqi security forces have reportedly arrested hundreds of alleged al-Qaeda members in and around Baghdad as part of a campaign the government is calling "Revenge for the Martyrs".
But the operations, which have taken place mostly in Sunni districts, have angered the Sunni community and failed to halt the violence.