The source of the call was not known, but authorities moved to halt its spread online. Searches for the word "jasmine" were blocked Saturday on China’s largest Twitter-like microblog, and the website where the request first appeared said it was hit by an attack.

Activists seemed not to know what to make of the call to protest, even as they passed it on. They said they were unaware of any known group being involved in the request for citizens to gather in 13 cities and shout "We want food, we want work, we want housing, we want fairness."

Some even wondered whether the call was "performance art" instead of a serious move in the footsteps of recent protests in Egypt, Tunisia, Bahrain, Yemen, Algeria and Libya.

China has limited reporting on the protests in the Middle East and quickly shuts down most protests at home.

Authorities appeared to be treating the protest call seriously. Families and friends reported the detention or harassment of several activists, and some said they had been warned not to participate Sunday.

Police pulled Beijing lawyer Jiang Tianyong into a car and drove away, his wife, Jin Bianling, said. She told The Associated Press by phone she was still waiting for more information Saturday night.

Su Yutong, an activist who now lives in Germany, said that even if Chinese authorities suspect the call to protest wasn’t serious, Saturday’s actions showed they still feared it.

"If they act this way, they’ll push this performance art into the real thing," she said in an e-mail.

In a Twitter post, Su listed at least 14 people who had been taken away and called that count incomplete.

Tensions were already high in recent days after a video secretly made under house arrest by one of China’s most well-known activist lawyers, Chen Guangcheng, was made public. Chen and his wife reportedly were beaten in response, and some of Chen’s supporters reported being detained or beaten by authorities after meeting to discuss his case.

The call for a "Jasmine Revolution" came as President Hu Jintao gave a speech to top leaders Saturday, asking them to "solve prominent problems which might harm the harmony and stability of the society."

The ruling Communist Party is dogged by the threat of social unrest over rising food and housing prices and other issues.

In the latest price increase, the National Development and Reform Commission announced Saturday that gasoline and diesel prices would be raised by $53 per ton.

The call to protest was first posted on the U.S.-based Chinese-language website Boxun.com. "Boxun has no way to verify the background of this and did not participate," it said.

The Boxun site was unavailable Saturday, and reported being attacked.

"This is the most serious denial of service attack we have received," it said in a statement. "We believe the attack is related to the Jasmine Revolution proposed on Feb. 20 in China."