The attack was carried out by the Alliance for a Free and Sovereign Congo (APCLS) in the Nyabondo area, around 70 kilometres north of the regional hub Goma in the restive province of North Kivu.
MONUSCO's military spokesman Felix-Prosper Basse told reporters in Kinshasa that one member of the UN force and three other soldiers were also wounded.
Basse accused the APCLS of opening fire on civilians during the raid, which he said forced hundreds of families to flee their homes and seek MONUSCO protection.
MONUSCO gunships were brought into action to hunt down the rebels, Basse said.
In mid-March, the UN's special intervention brigade and the Congolese army recaptured the town of Lukweti -- north of Nyabondo -- which the APCLS had used as its headquarters for six years.