The 15-member council unanimously agreed to put off a decision until May 26 "to examine thoroughly" recommendations put forward by UN Secretary General Ban Ki-moon.
Ban's recommendations largely follow the outline of a deal struck in N'Djamena between Chad and the UN mission known as MINURCAT under which the 3,300-strong force would be reduced to 1,900.
It would remain in place until at least October 15, after which it would gradually withdraw.
And from May 16, MINURCAT's mandate would no longer include the protection of civilians which the Chadian government wants to assume.
Chadian President Idriss Deby has criticized the UN mission as "a failure," and accused the troops of remaining behind the safety of their razor wire fences and not venturing out to help refugees.
But last month Amnesty International appealed for the peacekeeping forces to remain in Chad, after a recent spate of bloodshed in the east of the landlocked Central African country.
And UN agencies warned last week that the planned departure of the international peacekeepers could leave a security vacuum in eastern Chad, where humanitarian workers face constant attacks by bandits.
The UN mission, deployed in Chad and the neighbouring Central African Republic, was created in 2007 to protect refugees who have fled the war in Darfur, in neighbouring western Sudan.
It never reached its planned full contingent of 4,900 peacekeepers. In March 2009 it took over from the EU peacekeeping force EUFOR.
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