A Syrian opposition figure says supporters of President Bashar al-Assad have thrown tomatoes and eggs at the U.S. ambassador to Syria and tried to storm an office where the two men were meeting.
Hassan Abdul-Azim said a crowd of about 100 pro-Assad protesters was outside his Damascus office as he met with Ambassador Robert Ford.
Also Thursday, Syria's foreign ministry accused the United States of inciting violence against its security forces.
Meanwhile, the U.N. Security Council is considering a possible compromise resolution on Syria that avoids immediate sanctions, but condemns the escalating violence, as clashes between security forces and dissident soldiers continue.
The 15-member Council met Wednesday to discuss rival draft resolutions on the Syrian crisis drawn up by European powers and Russia.
France, Britain, Germany and Portugal proposed a new resolution in which they drop demands for immediate sanctions, but threaten Assad with action if he does not end his deadly crackdown on opposition protests.
Russia opposes any hint of sanctions, and the latest version of its draft resolution seeks to condemn violence by all sides in Syria. India, Brazil and some other non-permanent Council members also are against imposing punitive measures on Damascus.
Earlier attempts at an agreement ended in August with a presidential statement, which does not carry the same weight as a resolution. Diplomats say they hope to vote on the new draft by the end of the week.
Rights activists say three army deserters were killed Wednesday in a second-straight day of fighting in the central town of Rastan.
Syrian troops launched raids in Rastan seeking to crush dissident soldiers who are fighting back after months of mostly peaceful protests against the president.
The activists say dozens of armored vehicles entered Rastan early Tuesday, and army troops stormed hospital emergency rooms looking for wounded rebel soldiers. Dozens of people were reported taken from their homes.
The defectors, estimated to number in the thousands across the country, are part of the newly formed Free Syrian Army. The dissident soldiers are led by Colonel Riad al-Asaad, who defected from the air force in July.
President Assad has repeatedly sent out troops to quell anti-government protests. The United Nations says the crackdown has killed at least 2,700 people since mass protests started in March. Syria says the death toll is lower and includes members of the security forces.
Human Rights Watch has urged the U.N. Security Council to take action to stop what it calls Syria's "merciless campaign" of killings, torture and arbitrary detention.
Some information for this report was provided by AP, AFP and Reuters.