The six peacekeepers were part of the Indian contingent serving with the UN Organization Stabilization Mission in Democratic Republic of Congo (MONUSCO).
They were ambushed along with their interpreter while returning from a patrol with 12 other peacekeepers near Buganza in North Kivu province on October 17 after finding the bodies of four civilians, the mission said in a news release.
"This premeditated, targeted and deliberate attack is inadmissible," said the UN Secretary-General's Special Representative and head of MONUSCO, Roger Meece.
"We will work with the national authorities to identify those responsible for this ignoble deed so that they are called to justice."
A UN Indian peacekeeper was killed in the same province in July when he was caught in a cross-fire in clashes between Congo's armed forces and a rebel group known as the March 23 Movement (M23).
Congo's eastern provinces of North and South Kivu have witnessed increased fighting between government troops and the M23, which is composed of renegade soldiers who mutinied in April. The fighting has displaced more than 300,000 people, including many who have fled to neighbouring Rwanda and Uganda, as well as within DRC.
MONUSCO, with 19,000 uniformed personnel, is the latest iteration of UN peacekeeping missions that have helped to bring stability and civilian elections to the vast country after it was torn apart by civil wars and rebel movements.
Much of the country has achieved a measure of stability but fighting with various dissident groups has continued in the east where the bulk of the peacekeepers are deployed.