The United States imposed personal sanctions on Syrian President Bashar Assad on Wednesday, amid continued violent crackdowns on Syrian pro-democracy protests.

In a statement announcing the newly issued sanctions, U.S. President Barack Obama said the new measures were taken "in order to take additional steps with respect to the Government of Syria's continuing escalation of violence against the people of Syria."

That violence, the statement added, included "attacks on protestors, arrests and harassment of protestors and political activists, and repression of democratic change, overseen and executed by numerous elements of the Syrian government."

Beside Assad himself, the document lists the other senior Syrian officials sanctioned by the new measures as Assad, Syrian Vice President Farouk AL-Shara, Prime Minister Adel Safar, Minister of the Interior Mohammad Ibrahim al-Shaar, Minister of Defense Ali Habib Mahmoud, Head of Syrian Military Intelligence Abdul Fatah Qudsiya, and Director of Political Security Directorate Mohammad Dib Zaitoun.

A senior U.S. official said the new sanctions were meant to force Assad to carry out promised political reforms. "President Assad has a clear choice: either to lead this transition to democracy or to leave," the official, speaking on condition of anonymity, told reporters.

The unrest began two months ago when protesters, inspired by other Arab uprisings, called for greater freedoms and an end to corruption. The harsh crackdown on dissent by troops, security forces and irregular Assad loyalists led them to go further and demand an end to Assad's rule.

Assad had been partly rehabilitated in the West over the last three years but the United States and European Union condemned his use of force to quell unrest and warned they plan further steps after imposing sanctions on top Syrian officials.

The Syrian leader told a delegation from the Damascus district of Midan that security forces had made mistakes handling the protests, Wednesday's al Watan newspaper said.

One delegate said Assad told them 4,000 police would receive training "to prevent these excesses" being repeated, it said.

Human rights groups say Assad's crackdown has killed at least 700 civilians. Authorities blame most of the violence on armed groups backed by Islamists and outside powers, saying they have also killed more than 120 soldiers and police.

The Obama administration has tightened sanctions on senior Syrian officials to try to pressure Damascus to halt its crackdown on pro-democracy protests, but international human rights groups have criticized Washington for not taking stronger action.