Beijing (CNN) -- The U.S. ambassador to China said Monday that American and other foreign journalists were "illegally detained or harassed as they attempted to do their jobs" while covering protests in downtown Beijing over the weekend.

Ambassador Jon Huntsman Jr. said in a statement that one reporter was "severely beaten and detained for many hours."

"I call on the Chinese government to hold the perpetrators accountable for harassing and assaulting innocent individuals and ask that they respect the rights of foreign journalists to report in China," he said.

Journalists including CNN's Eunice Yoon and Jo Ling Kent were physically harassed by Chinese security Sunday as they planned to cover a protest -- which never took place, perhaps because of heavy police presence.

They were shoved, dragged and at times carried away from the scene. Their cameras were confiscated and footage was deleted, and a press card was taken away from Yoon, who wrested it back from an officer who refused to give his name.

"We found out many other journalists were treated the same and, in some cases, much worse," Yoon wrote. "A former colleague and friend of mine, Steve Engle of Bloomberg News, had been dragged into an alley by several police who beat him up. He ended up at the hospital."

China's foreign affairs ministry did not respond to a request for comment from CNN Monday.

The heavy security was a response to a second weekend in a row of anonymous calls by organizers for a pro-democracy demonstration in Beijing.

Hundreds of Chinese police officers along with more than 120 vehicles flooded Beijing's central pedestrian shopping area, Wangfujing, on Sunday, around the site of a second attempted "jasmine" rally inspired by pro-democracy protests in Tunisia.

There was no sign of protest as the police deployed unusual tactics to prevent demonstrations.

At Beijing's Wangfujing shopping area, a large number of plainclothes and uniformed police officers circulated the area, which is typically known for being an open area attracting throngs of domestic and foreign tourists. Every entrance to the shopping area was guarded by multiple police officers on Sunday.

In front of a McDonald's restaurant, the appointed meeting place for demonstrators, a large construction site was erected several days ago following the first attempted demonstrations, directly blocking the open plaza outside the restaurant.

Nearby, a mysteriously large group of orange-clad street sweepers stood near the appointed protest area with brooms but did not sweep the street.

When protests were slated to begin, two large street-washing trucks began slowly driving through the main thoroughfare, blocking pedestrian traffic and spraying water.

Plainclothes police sat in restaurants and storefront windows for hours, observing the surroundings, while uniformed police officers forced journalists and onlookers out of the vicinity.

In Hong Kong, approximately 25 concerned citizens who organized on Facebook gathered in the city center and carried placards and wore jasmine flower pins.

Placards read, "Freedom and Democracy. End One Party Rule. Push for Political Reform."

One Hong Kong demonstrator, Lam Ng, called for the end of single-party governance. "I don't agree with the Chinese government," he said. "I don't like the corruption."

Meanwhile on Sunday morning, just hours before the demonstration was slated to begin, Chinese Premier Wen Jiabao participated in his third annual web chat with selected internet users.

He did not comment on the protests planned for last week or Sunday.

Efforts to organize an earlier protest on February 20 were deemed largely unsuccessful after casual observers and police outnumbered the few protesters that showed up for the demonstrations.

Huntsman, wearing a black leather jacked with a patch of the American flag on his left shoulder, was captured at last week's protest in a widely viewed video posted on YouTube, in which he's called out by some in the crowd.

One asks if he is "hoping China will become chaotic?" -- a reference to the unrest that has consumed several countries in Africa and the Middle East as protesters there demand democracy.

Speaking in Mandarin, Huntsman tells them that he "just came to have a look." The hecklers accuse him of pretending to not know about the protest and feigning ignorance.

U.S. Embassy spokesman Richard Buangan said Huntsman came upon the protests when he was passing through the area with his wife, two of his children and his son-in-law.

"Last Saturday, (members of) the Huntsman family were on their way to visit a Tiananmen Square museum, passing through Wangfujing Shopping district.

The Huntsmans walking through Wangfujing, and the events that took place related to any so-called protests, were purely coincidental. Once the family realized a security-related situation was developing, they immediately left," Buangan said.

CNN's Jo Ling Kent contributed to this report.