The demonstrators took to the streets in the region on Tuesday to condemn the Riyadh regime for the deadly crackdown on protests.
On July 8, security forces opened fire on demonstrators in Qatif, killing three people and injuring several others.
The protesters were demonstrating against the detention of prominent cleric Sheikh Nemr al-Nemr, who was attacked and arrested earlier in the day.
Since February 2011, protesters have held demonstrations on an almost regular basis in Saudi Arabia, mainly in Qatif and the town of Awamiyah in Eastern Province, calling for the release of all political prisoners, freedom of expression and assembly, and an end to widespread discrimination.
However, the demonstrations have turned into protests against the Al Saud regime, especially since November 2011, when Saudi security forces killed five protesters and injured many others in Eastern Province.
Similar demonstrations have also been held in the capital and the holy city of Medina over the past few weeks.