Further troop withdrawals will be considered according to "the situation on the ground," the UN said.
The UN has also changed the name of the peacekeeping force, rebranding it as a "stabilisation mission," a move intended to appease the government.
UN peacekeepers first arrived in the Congo in 1999, at the end of a four-year civil war.
They were often ill-equipped, and have been accused of corruption, but many observers credit the force with preventing even worse bloodshed in the country, which has faced an ongoing problem with rebel forces throughout the last decade.
Congo's national army is widely considered corrupt and ineffective.