While other nations are in favor of such a deployment, U.N. Deputy Secretary General Jan Eliasson said Mali has not given "a clear green light" for such an operation, the BBC reported Tuesday.
Thousands of troops from France and African nations have helped recapture major towns in northern Mali from Islamist militants who have controlled the region since April 2012.
Most of the towns were taken without a fight, but residents of Gao, the region's biggest town, suffered through four hours of fighting Sunday. The town is now said to be calm.
Responsibility for the weekend violence was claimed by the Movement for Oneness and Jihad in West Africa (Mujao).
Eliasson said despite Mali's "hesitation," the "trend" favored sending in U.N. peacekeepers after the "combat phase" was over.
France has said it wants to begin withdrawing its 4,000 troops in March.
Should the United Nations approve a peacekeeping force, the bulk of the troops would likely come form African countries that already have soldiers fighting in Mali.