In Bukavu, capital of South Kivu province, hundreds of people calmly marched to demand the liberation of parts of neighboring North Kivu occupied by M23 guerrillas, according to AFP reporters.
M23, or March 23 Movement, a largely Tutsi group, has been on the offensive over the past two years in North Kivu, with combat recently intensifying around the provincial capital, Goma.
"The years pass, the dead, the suffering and the trauma multiply in this part of the country," said Adrien Zawadi, president of a local civil society organization, who added that "It must end."
Western governments and the United Nations accuse Rwanda of supporting the M23, though Kigali denies the claim.
Demonstrators called for the closure of borders with Rwanda and Uganda, which has also been accused of supporting the rebels. Some also called for the severance of relations with the United States, France and Britain for their presumed connivance with Rwanda.
A similar demonstration in Kisangani in Tshopo province called for a declaration of war against Rwanda and the end of diplomatic relations with allegedly complicit Western countries.
Several hundred women on Wednesday marched in the capital Kinshasa to call for an end to the war, while a few youths burned cars and tires outside Western embassies and United Nations offices.