The rebel coalition toppled the government in CAR in March, forcing President Francois Bozize to flee to neighboring Cameroon.
U.N. special envoy to CAR Margaret Vogt told the Security Council that Seleka has turned on the civilian population and pushed the country into a "state of anarchy."
The United Nations estimates at least 173,000 people were internally displaced and another 50,000 fled to neighboring countries to escape the conflict. The rebel group is accused of committing crimes against humanity despite agreeing to a peace accord in January.
Vogt described the situation in CAR as "horrifying."
Interim Prime Minister Nicolas Tiangaye, who's managed to maintain his position despite rebel claims to power, told the Security Council that military intervention was needed in CAR before conflict spills over the borders.
He called on former colonial power to intervene "with force" to disarm Seleka. The European Union and African Union were called on to finance the mission.