Minor clashes broke out in Amman on Friday night between supporters and opposers of King Abdullah II of Jordan.
Thousands of demonstrators chanted the Arab Spring slogan “the people want the downfall of the regime”.
The country has avoided the unrest that has swept through the region over the past two years, but a decision to raise fuel prices has sparked protests and unrest.
The incidents took place near Amman’s wasfi al-Tal Square with supporters of the regime attacking protestors. The violence comes after three days of protests.
Demonstrations outside the capital since Wednesday had turned violent in areas inhabited mainly by tribes, who now form part of the minority. They are outnumbered by Jordanians of Palestinian origin.
The ruler cancelled a visit to London he had been due to make next week, without giving details for the decision.
Instability in Jordan would come at a dangerous time for the region, with Syria’s war continuing and the Israel – Gaza crisis escalating.