Robert Ford, the U.S. ambassador to Syria, was pelted with tomatoes by supporters of President Bashar Assad as he arrived at ...

Robert Ford, the U.S. ambassador to Syria, was pelted with tomatoes by supporters of President Bashar Assad as he arrived at an office in Beirut for a meeting with a Syrian opposition leader Thursday.

Assad supporters tried to storm the office, breaking some door locks, reports the AP. Office staff prevented them from rushing in.

About 100 pro-Assad protesters demonstrated outside as Ford met with Hassan Abdul-Azim, a leading Syrian opposition figure. Azim was the first to tell the press about the incident.

This is not the first time that Ford has been attacked in Syria. The ambassador was harassed by pro-Assad protestors in late August after he raised the ire of Syrian authorities by taking a surprise trip to the city of Jassem, which has been a flashpoint for anti-government protests.

The Syrian government reacted by delivering a diplomatic note of protest to the United States, contending that Ford had not been authorized to travel there. The Assad regime also encouraged its supporters to throw rocks and eggs at the U.S. embassy.

Tensions between the U.S. and Syria have escalated in recent months. Ford’s provocative trip to Jassem, the second such trip to areas that have been centers of protest against the Syrian government, comes in the context of increasingly aggressive calls from the U.S. that Assad step down.

“His calls for dialogue and reform have rung hollow while he is imprisoning, torturing and slaughtering his own people,” President Obama said in August. “For the sake of the Syrian people, the time has come for President Assad to step aside.”

Azim said that Syrian security forces arrived about an hour after Thursday’s attack began.