The rebel Seleka coalition, comprised mostly of Sunni militias, toppled the government of the Central African Republic in March. The conflict has taken on a religious tone as Christian fighters take on their Sunni Muslim rivals.
"Serious human rights violations are being committed on religious grounds, as well as the looting and destruction of property," the spokeswoman said in a statement from Geneva.
The U.N. Security Council backed a mandate for a French military role in CAR to help support an African Union peacekeeping mission. Two Frenchmen died as a result of injuries suffered during recent fighting in Bangui, the CAR capital.
CAR is a former French colony. The U.S. and British militaries have offered non-combat support to their French counterparts.
Shamdasani said the situation in Bangui has improved in recent days though there were lingering causes for concern.
"While we welcome the fact that religious leaders have been calling for calm and reconciliation between Muslims and Christians, we urge them to redouble their efforts to contain rising intolerance and inter-communal violence," she said.