Hundreds of young Congolese men took to the streets of Kinshasa to express their outrage at the entry of the M23 rebels in the eastern city of Goma.
They barricaded roads and attacked the embassies of Rwanda, Uganda, France, and the United States.
The French embassy was set on fire and vandalised.
The locals accuse the governments of the foreign missions of supporting Rwanda, which UN experts earlier said was backing the M23 rebels.
Rwanda has denied the charge and blamed the DRC for supporting a Hutu militia seeking to topple its government.
On Monday, the M23 rebels marched into the city of Goma and said they had captured it from government forces.
But fighting has been going on for the control of the strategic city that is the capital of the mineral-rich province of North Kivu.
The African Union and the United Nations Security Council are set to hold emergency meetings to discuss ways of preventing the conflict from escalating further.
The rebels—supported, the United Nations says, by thousands of Rwandan soldiers—made a lightning advance on the city in the eastern Democratic Republic of Congo on Sunday.
The M23 says it is in control of the provincial capital, but the Congolese authorities dispute this, with conflicting reports from officials as to how much it claims to hold.
Residents and journalists on the ground confirm having seen M23 rebels patrolling some streets, notably in the western part of the city.
With internet services cut, radio stations not broadcasting, and phone connections intermittent, the only news is by word of mouth.
Meanwhile, thousands of civilians continue to flee the area.