The Obama administration ramped up the pressure on Syrian President Bashar al-Assad on Wednesday with economic sanctions that targeted his personal finances and linked him explicitly to human rights abuses in his government’s brutal, two-month-old crackdown on demonstrators.

The sanctions, which named six other top Syrian officials, represented a significant escalation in the administration’s public criticism of the Assad regime, marking the first time the ruler was penalized for the ongoing clashes that have left more than 900 people dead and thousands in prison. The White House did not assert that Assad should resign.

The economic measures, although largely symbolic, appeared to embolden the country’s anti-government movement. Widespread demonstrations were reported after nightfall Wednesday as opposition leaders cheered the mounting international pressure on Assad.

“President al-Assad and his regime must immediately end the use of violence, answer the calls of the Syrian people for a more representative government and embark upon the path of meaningful democratic reform,” David S. Cohen, the Treasury Department’s acting undersecretary for terrorism and financial intelligence, said in announcing the move.

The executive order signed by President Obama essentially freezes any U.S. assets owned by Assad or other top security and political officials. The others named are Vice President Farouk al-Charaa, Prime Minister Adel Safar, Interior Minister Mohammad Ibrahim al-Shaar, Defense Minister Ali Habib Mahmoud and two intelligence chiefs: Abdul Fatah Qudsiya, the head of military intelligence, and Mohammed Dib Zaitoun, director of the Political Security Directorate.

Syria’s state-run television condemned the sanctions Thursday, the Associated Press reported, saying they “serve Israeli interests” and will not affect Syria’s future decisions.

It was the second round of sanctions against Syria in three weeks. A senior administration official involved in preparing the sanctions said the White House was responding to sharply deteriorating conditions in Syria, where unarmed demonstrators have been attacked by government tanks in at least two cities.

Administration officials did not quantify how much property, if any, is owned by Assad and his inner circle. But Elliott Abrams, who was a top national security adviser to President George W. Bush and is a frequent critic of the Obama administration’s foreign policy, said singling out Assad for sanctions was an important move, even if mostly symbolic.

“Many Syrians believe the Obama administration wants Assad to stay in power,” Abrams said. “This move helps change that view.”

Abrams said the White House should follow up by calling for Assad’s departure. “The Assad regime is vicious, violent, corrupt and unreformable, and we should say so,” he said.

Although it has repeatedly condemned the violence in Syria, the Obama administration has stopped short of calling for Assad’s resignation or saying that he has lost legitimacy as Syria’s leader.

Protesters have continued to take to the streets in towns and cities across the country on successive Fridays over the past eight weeks, despite a massive security crackdown in which tanks have bombarded residential neighborhoods and thousands of people have been detained. Wissam Tarif of Insan, a human rights group based in Spain that concentrates on the Middle East and North Africa, said he has recorded 920 deaths.

Demonstrations were reported in numerous Syrian towns Wednesday evening, suggesting that the protest movement has been energized. Night protests have been taking place on weekdays in Syria, but an unusual number of towns reportedly joined in Wednesday.

Videos posted on YouTube showed protesters marching in the darkness in Homs, Hama, Idlib and several other locations, including Midan, the only neighborhood of Damascus where there have been significant attempts to demonstrate.

The crackdown has failed to deter demonstrations in protest flash points, but the opposition movement has not made significant inroads into the capital or Syria’s largest city, Aleppo, denying the protesters the critical mass that forced the fall of the presidents of Egypt and Tunisia.

A general strike called by the opposition for Wednesday fizzled, with most shops and businesses in Damascus and Aleppo remaining open.

Protesters “have felt in the last eight weeks that they’ve been left alone by the international community,” Tarif said. “There’s no doubt that these sanctions will encourage the Syrian street and will generate a feeling that Assad is accountable.”

But whether sanctions will spur the regime to relax its iron-fisted policy against its opponents is in doubt. The government has shown signs in recent days that it is feeling the building international heat. On Wednesday, Assad was quoted in the official al-Watan daily as acknowledging mistakes by the Syrian security forces.

He told a visiting delegation of elders that there had been “wrong security practices,” the newspaper quoted a member of the delegation as saying.

After the scale of protests Friday made it clear that the brutality had failed to suppress the opposition, the government offered a “national dialogue” with opposition leaders and admitted that there were widespread and peaceful protests with legitimate demands for reforms. Yet, the following day, the crackdown escalated.

“The Assad regime is on a very slippery slope,” said Murhaf Jouejati, professor of Middle East studies at Washington’s National Defense University. “Even with cosmetic reforms, I don’t think they’re going to satisfy the protest culture of resistance that has emerged on the streets.”

Sly reported from Beirut.