Calling for political reforms, the demonstrators on Wednesday once again took to the streets and condemned the authorities for arresting peaceful protesters and activists.
The rally comes in the wake of the security forces’ detaining of several people in Qatif over the past week.
The demonstrators also expressed their solidarity with prominent Egyptian rights activist and lawyer Ahmed al-Gizawi who was arrested earlier in the Saudi city of Jeddah.
Gizawi was arrested by Saudi security forces on April 17 upon arrival in Jeddah. The lawyer's detention came without any prior notification and at a time he was in Saudi Arabia for Hajj pilgrimage.
Egypt's Arabic Network for Human Rights Information issued a statement last month, saying Gizawi's detention followed a sentence of one year in prison and 20 lashes delivered against him in absentia for criticism of the Saudi rulers.
Gizawi is being targeted for his activism in favor of Egyptian detainees in Saudi prisons, the statement added.
His arrest has strained relations between Riyadh and Cairo.
Saudi Arabia's east has been the scene of anti-government protests since February 2011, with demonstrators demanding rights reforms, freedom of expression and the release of political prisoners.
Amnesty International and Human Rights Watch have also criticized the Al Saud regime for silencing dissent through intimidation and the violation of the basic rights of citizens.