The rebel Seleka coalition took Bangui by force last weekend. President Francois Bozize fled the country, though rebel leaders said they'd honor the terms of a January truce with the government.
The Security Council condemned the rebel seizure of power, taking note of an Arab League decision to suspend CAR's membership.
"The members of the Security Council called on all parties to refrain from any acts of violence against civilians, including foreign communities, to allow safe and unhindered humanitarian access consistent with international law," a council statement read.
The International Criminal Court issued similar concerns about possible crimes committed as rebels advanced on the CAR capital.
"Those who seek to attain or retain political power by targeting civilians will be held accountable," the ICC said.
The BBC reports Tuesday that rebel leaders suspended the state constitution. The terms of the January peace deal call for new elections within three years.