At least two children have been beheaded since fighting began in the capital Bangui Dec. 5, the U.N. organization said in a statement released Monday.
"We are witnessing unprecedented levels of violence against children. More and more children are being recruited into armed groups, and they are also being directly targeted in atrocious revenge attacks," said Souleymane Diabate, UNICEF's representative in the CAR.
Diabete called on armed groups to prevent violence against children, tell members to stop recruiting minors to be fighters and immediately release all children associated with the groups.
UNICEF also called on groups to ban attacks on health and education providers and to allow unhindered passage for humanitarian assistance.
International medical aid group Medecins Sans Frontieres, or Doctors Without Borders, said in a statement the situation in Bangui appears to "out of control," with clashes, lynchings and violent attacks a daily occurrence.
Since early December, MSF said medical teams had treated more than 1,000 people caught up in the violence. Between 15 and 20 new patients arrive every day.
Nearly 430 patients have been hospitalized from either gunshot wounds or machete blades.
MSF also said health facilities and healthcare workers had been threatened. On Dec. 24, an armed man entered the MSF dispensary at the Bangui airport, while a man armed with grenades entered a hospital. On Sunday, an ambulance was prevented from picking up wounded and the ambulance staff threatened.
None of the incidents resulted in any harm, MSF said.