The demonstrators took to the streets in central province of al-Qassim on Friday, calling for the immediate release of political prisoners including Mohammed al-Qahtani.
The protestors also urged an immediate trial of Saudi Interior Minister Mohammed bin Nayef.
Earlier on March 9, a Saudi Arabian court sentenced two prominent political and human rights activists Mohammed Fahd al-Qahtani and Abdullah Hamad to at least 10 years in prison.
The activists were founding members of the Saudi Civil and Political Rights Association, known as Acpra, that documents human rights abuses and has called for a constitutional monarchy and elections.
Saudi activists say there are more than 30,000 political prisoners, mostly prisoners of conscience, in jails across the Kingdom.
According to the activists, most of the detained political thinkers are being held by the government without trial or legitimate charges and that they were arrested for merely looking suspicious.
Some of the detainees are reported to be held without trial for more than 16 years.
Attempting to incite the public against the government and the allegiance to foreign entities are usually the ready-made charges against the dissidents.