UN Secretary-General Ban Ki-moon said the document sets the stage for an "enhanced" UN role in key areas.
"The United Nations is deeply committed to helping the people of Iraq, and I am pleased to have the opportunity to now enhance, where possible, our contributions in crucial areas such as national reconciliation, regional dialogue, humanitarian assistance, and human rights," Ban told the 15-member Security Council, according to a UN statement.
The resolution authorizes the United Nations, at the request of the Iraqi government, to help promote political talks among the country's ethnic and religious groups.
"A peaceful and prosperous future is for Iraqis themselves to create, with the international community lending support to their efforts," Ban said.
The new resolution also authorizes the UN to promote a regional dialogue on issues including border security, energy, and refugees.
The United States and Britain co-sponsored the resolution.
The UN dramatically curtailed its presence in Iraq in the wake of a bomb attack in August 2003 that killed the UN secretary-general's special representative for Iraq, Sergio Vieira de Mello, along with 21 others.
UN staff began returning staff to Iraq in April 2004.
The UN Press Center says there are currently "almost 300 international staff and nearly 400 national staff in Iraq, Kuwait, and Jordan."
(with additional agency reports)