"The arrival of international forces in Bangui [the nation's capital] and their deployment beyond the capital represent the only hope of security for millions of people who have been living in fear most of this year," the European Union's top aid official said Sunday.
The EU said it established an "air bridge" to ferry humanitarian goods and personnel from Cameroon to CAR. Daily flights began Sunday.
The EU estimates nearly half a million people in CAR are displaced by fighting.
"In recent days we have heard horrific stories of massacres from CAR," Georgieva said.
The Seleka rebel coalition, a largely Muslim group, toppled the CAR government in March. The fighting has since escalated as Christian militias take up arms against their Muslim rivals.
Last week, the U.N. Security Council approved of a French military mission to support African Union peacekeepers in the country.
Arnaud de Baecque, deputy director for CAR operations for the International Committee of the Red Cross, said Saturday he was "extremely" worried about the situation in the country.
The ICRC said recent fighting near the capital city has left at least 300 people dead and the number keeps rising.
"The fighting has taken a heavy toll among the population," de Baecque said.