In the country's largest protest in months, around 7000 people had marched in the Sitra quarter of the capital demanding reforms.
It was organised by al-Wifaq National Islamic Society, a group that enjoys strong support from Bahrain's Shia Muslims, who make up a slight majority of the kingdom's 400,000 citizens but complain they are discriminated against by the country's Sunni Muslim leadership.
"Constitutional reforms is what the whole nation is after. We are hoping to have a new constitution which guarantees more rights to the people," al-Wifaq spokesman Abd al-Jalil Singace said on Tuesday.
"We are moving one step at a time and this campaign for constitutional reforms will not cease even if they put a freeze on our activities," Singace said without elaborating.
Bahraini officials were quoted in a pro-government newspaper as saying that the authorities would take legal action against the society for defying a government order banning Friday's rally.
Shia leaders want King Hamad to
carry out far-reaching reforms
Bahraini officials could not be immediately reached for comment on Tuesday. The newspaper reports did not specify what kind of steps the government might take.
Singace said the political society was "not officially notified" of the ban against the rally and has so far not heard of any legal actions yet.
Al-Wifaq is demanding constitutional changes, particularly to eliminate amendments giving the upper house of parliament - which is appointed by the king - as much power as the elected lower chamber.
In October 2002, Bahrain held its first democratic parliamentary elections since 1973 after the ruler, Shaikh Hamad bin Isa Al Khalifa, won the approval of a new constitution in a vote the year before.
The charter called for a parliament (which had not existed since 1975), an independent judiciary and a body to investigate public complaints.
"This campaign for constitutional reforms will not cease even if they put a freeze on
Abd al-Jalil Singace, spokesman, al-Wifaq National Islamic Society
But al-Wifaq and three other groups boycotted the October 2002 elections, in part because of their objection to the equal powers between the two houses of parliament.
Bahrain's ruling family hails from the Sunni branch of Islam. During the mid-1990s, Shia staged a violent campaign for political reform, triggering a government crackdown.
More than 40 people were killed in the unrest.