Several thousand people have held a protest outside the United Nations' offices in Bahrain's capital, Manama.
The demonstrators chanted "Down, Down, Khalifa" - a reference to long-serving Prime Minister Sheikh Khalifa Bin Salman al-Khalifa, activists said.
They also carried banners urging the UN to "intervene to protect civilians".
Witnesses said that police allowed the peaceful demonstration to proceed without interference, while a police helicopter hovered overhead.
One activist told the BBC: "Today the police were good. They didn't close off roads, they didn't attack us as they usually do with tear gas and stun grenades."
Observers say the police might have behaved with restraint because of a rare public rebuke by the United States last week over police tactics and the beating of a well-known human rights activist, Nabeel Rajab.