The riot comes after the recent political turmoil hit Tunisia and Egypt, spreading the fear among Saudi officials that the” domino effect” in the Arab states likely to target Riyadh.
According to reports, scores of people were detained by the security forces.
It is believed that the demonstrations came in reaction to a call by Blackberry smart phones on Thursday, calling on the people to pour into the streets.
Saudi security forces were surprised due to the spontaneous protests, because according to the message circulated via the Blackberry gadget, the demonstrations were due to be held on Saturday.
A massive turnout is expected in Jeddah today, where the protesters plan to protest against social and economic problems of the kingdom and call for political reforms.
Similar messages spread throughout Saudi state and private administrations, inviting the staff to go on general strike.
Saudi police mobilized an army of military vehicles and cordoned off the protesters to detain all protesters, but some fled the scene.
The unrest was kicked off by a group of women before men stream to join the protesters, Taqrib News Agency (TNA) quoted Al-Jazeera network.
Protesters also chanted slogans and called for the change of their political establishment.
Flood also hit Jeddah last Friday, knocking down power in some parts and incurred damages to some vehicles.
At least four people were killed in the flood.