"Activists and human rights defenders have sought refuge in the UN house in Manama, Bahrain, where they asked for intervention for their protection and safety against the state terror," the Committee of Solidarity with Activists and Detainees of Conscience in Bahrain said on Wednesday.
The statement added that state security forces had threatened to remove the activists, a claim denied by officials.
It also said one of the group had been on hunger strike since 30 November and had been joined by the others.
The activists represented the Bahrain Centre for Human Rights, National Committee for Martyrs and Victims of Torture, the Unemployed Committee and the Decent Housing Committee.
The incident follows a protest on Friday in which thousands of Bahrainis marched in Manama following a call by four political opposition groups to protest against the alleged beating and sexual assault of Musa Abedali, an activist from a group representing the unemployed.
The Abedali said he was beaten and sexually assaulted during a demonstration last week broken up by security forces.
Bahrain's elected chamber, scrapped in 1975, was revived in 2002 as part of reforms spearheaded by King Hamad which turned the Gulf state into a constitutional monarchy.
All four opposition groups boycotted the 2002 parliamentary polls in protest at the amendment to the 1973 constitution which split legislative power equally between the elected chamber and the consultative council.