WASHINGTON (AP) — The Obama administration said Friday it had read the "riot act" to Syria's ambassador to the United States over an attack on the top U.S. envoy to Syria.

The State Department said Syrian Ambassador Imad Moustapha had been summoned to the building late on Thursday to formally condemn the assault on American Robert Ford earlier in the day. The dressing-down was delivered by the top U.S. diplomat for the Mideast, Assistant Secretary of State for Near Eastern Affairs Jeffrey Feltman, it said.

Moustapha was "read the riot act about this incident," spokeswoman Victoria Nuland said in unusually blunt terms. "He was reminded that Ambassador Ford is the personal representative of the president and that an attack on Ford is an attack on the United States."

"We expressed our disgust with this attack, and the Syrian government's failure to prevent it or adequately respond to it," she said.

Feltman's meeting with Moustapha followed strong condemnation of the attack by Secretary of State Hillary Rodham Clinton and the White House. They said the assault was part of a campaign to intimidate diplomats looking into Syrian President Bashar Assad's government's brutal repression of pro-reform demonstrators.

Ford and several colleagues from the U.S. Embassy in Damascus were pelted with tomatoes and eggs but were not injured in the incident outside the office of a Syrian opposition figure they were meeting. Several armored embassy vehicles were damaged by members of a violent pro-government mob wielding bricks, concrete blocks and iron bars.

Nuland said the U.S. is demanding compensation for the damage and is renewing demands for compensation for damage caused to the U.S. Embassy in Damascus by another pro-government mob in July.