"No going back; we will continue our protests," read banners carried by demonstrators who were gathered at the Shiite-populated village of Al-Deir, near the airport.
"Peaceful, peaceful, our revolt is peaceful," they chanted, as others held up banners that read "Down Hamad" in reference to Bahrain's king, the witnesses said.
The Gulf state's largest opposition grouping, Al-Wefaq, has called for a week of daily demonstrations and sit-ins to last through the end of the controversial Grand Prix race scheduled for April 22.
Al-Wefaq said the pro-democracy protests under the banner of "steadfastness and challenge" would take place in Shiite villages on the outskirts of Manama.
Bahrain, where the majority of the population is Shiite Muslim, is ruled by the Sunni Al-Khalifa dynasty.
On Friday, both the sport's governing body, the FIA (Federation Internationale de l'Automobile), and commercial rights holder Bernie Ecclestone announced the race will take place as scheduled.
The F1 race in Bahrain was cancelled last year in the wake of the Shiite-led uprising and the brutal government crackdown that followed in which 35 people were killed, according to an independent probe.