Bahraini police wounded several people on Saturday morning when they fired sound bombs, tear gas and bird shot to disperse dozens who protested across several Shiite areas, witnesses said.
"Down Hamad," chanted dozens of supporters of the youth group of the "Revolution of February 14," referring to Bahrain's Sunni monarch. "The people want to overthrow the regime."
"We have the right to choose our destiny," they chanted, waving the kingdom's red and white flag.
An exact toll of those hurt cannot be obtained, as wounded protesters are treated in homes from fear of being arrested in hospital.
Hundreds took part in similar protests near Manama on Friday calling for the release of opposition detainees, witnesses said.
And on Wednesday, leading Shiite rights activist Nabil Rajab was re-arrested pending a probe into tweets deemed insulting to Sunnis, prosecutors said.
Rajab led anti-government protests following a government crackdown on Shiite-led demonstrations against the regime in March 2011.
The six members of the Gulf Cooperation Council, a grouping of the Sunni Arab monarchies in the Gulf, have been discussing a Saudi proposal that would lead to a form of closer political union.
The first step in this process would be the union of Sunni-ruled Bahrain, which has a Shiite majority, with Sunni-dominated Saudi Arabia.
The proposal has prompted protests from Bahraini Shiites, who insisted that a referendum must be held for such a proposal to be endorsed.