The United States denounced Syria's army as "barbaric" and "reprehensible" after the latest violence, renewing its charges that President Bashar al-Assad has lost legitimacy.
The State Department highlighted the death of 12-year-old boy Talhat Dalat, who human rights activists said died of his injuries on Saturday after a policeman earlier shot him at close range during an anti-regime rally.
"The behavior of Syria's security forces, including other such barbaric shootings, widescale arrests of young men and boys, brutal torture, and other abuses of basic human rights, is reprehensible," State Department spokeswoman Victoria Nuland said in a statement.
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"President Assad must understand that he is not indispensable, and we believe he is the cause of Syria's instability, not the key to its stability," she said.
"The regime should make no mistake that the world is watching, and those responsible will be held accountable for their crimes," she said, repeating Secretary of State Hillary Clinton's remarks that Assad has "lost legitimacy."
Syrians have been taking to the streets almost daily since March 15 to demand democratic changes amid a wave of protests across the Arab world. At least 1,486 civilians have died in Syria, according to human rights groups.
Under pressure, state media said Sunday that Syria's cabinet has adopted a draft law to operate alongside the ruling Baath Party. But violence has persisted, with activists saying the army has consolidated its grip on the hotbed city of Homs.
US Ambassador Robert Ford and French Ambassador Eric Chevallier on July 7 visited another hotbed city, Hama, triggering strong condemnation from Syria. Crowds attacked the US and French embassies.
Nuland, speaking earlier at a press briefing, voiced alarm at signals that Syria wanted to restrict Ford's movements but said that the United States has not received any formal notification from Syria.
"Whether it is in Syria or anywhere else in the world, we reserve the right for our diplomatic personnel at all levels to travel as necessary to do their jobs, to represent US views to a broad cross-section of population and leaders, but also so that we can gather the information that we need to evaluate internal dynamics," she said.
President Barack Obama appointed Ford through a controversial tactic that bypasses Congress, where lawmakers of the rival Republican Party had said it was wrong to send an ambassador to Syria.
