The protesters took to the streets in response to a call by the February 14 Youth Coalition for rallies against a blockage imposed on the Shiite locality of Mahazza, near the capital, since November 7.
"The blockade will not make us afraid" and "Down with Hamad," chanted the protesters, in reference to King Hamad.
The protesters, some of whom wore masks, waved the Bahraini flag and pictures of prisoners.
Police responded by firing tear gas, sound bombs and buck shot, injuring some of the protesters, according to the witnesses who did not specify the number of casualties.
People injured at anti-government demonstrations in Bahrain avoid going to hospital for fear of being arrested.
In the latest clashes, police detained several demonstrators, and the skirmishes continued until dawn on Saturday, according to the witnesses.
Demonstrations have shaken Bahrain since its security forces crushed a Shiite-led uprising against the ruling Sunni regime in March last year.
The United States last week expressed concern about rising violence in Bahrain, one year after an inquiry report was issued on the violence, saying the country needed to put more of its recommendations into effect.