Former colonial power France "has the tendency to abandon us," a protester said as the group arrived from an earlier sit-in outside the US embassy. "We no longer need France, France may as well take its embassy and leave."
Protesters close to embattled President Francois Bozize had begun their US embassy protest chanting calls for peace just as rebels approaching Bangui called on forces loyal to Bozize to lay down their arms.
But the peaceful protest moved to the French embassy where the mood turned violent and demonstrators broke windows and pulled down the French flag.
"This situation is completely unacceptable," said French ambassador Serge Mucetti.
"I ask the government of the Central African Republic to respect the appropriate agreements on this matter. Those who acted in such a manner are enemies of the Central African Republic," he said.
A student demonstrator at the scene accused France of "not respecting defence agreements" linking the two countries.
The offices of Air France were also attacked, an AFP reporter witnessed.
Since the end of colonisation in the 1960s, French troops stationed in western Africa have often come to the help of former colonies whose regimes were on the verge of being toppled.
The Seleka rebel coalition now controls large swathes of the north and the east of the country.
Neighbouring Chad has sent troops into the country after a request from Bozize to try and stem the rebel advance.
Seleka is made up of rebels who say the government has not honoured peace accords signed between 2007 and 2011, which offered financial support and other help for insurgents who laid down their arms.