There were no details on the condition of the peacekeepers. An unspecified number of other peacekeepers in the contingent were injured by stone throwers when a base in South Kivu province was surrounded by crowd of 1,000 people, the United Nations said.
"The seven wounded peacekeepers have been taken to Goma, North Kivu, for medical treatment," Martin Nesirky said in a statement.
The United Nations said the protest was against attacks by Rwandan Hutu rebel FDLR forces in the area, and it suspected that local Mai Mai militia shot at the blue helmets from within the crowd.
Reinforcements have been sent to the area, which is calm but tense, the UN added.
Congo's last war officially ended nearly a decade ago but its east is still plagued by a plethora of local and foreign armed groups.
The UN mission in Congo is one of the world's largest, but its men are stretched thinly across the vast nation and the force is frequently accused of not doing enough to protect civilians from gunmen.
