The workers were cited and released for misdemeanor trespassing after they blocked the front entrance of the hotel, Unite Here Local 2 spokeswoman Riddhi Mehta-Neugebauer said.
About 360 members and supporters of Unite Here Local 2, which represents hospitality workers for the Chicago-based hotel chain, gathered at the protest at about 4:30 p.m.
Most of them picketed in front of the Hyatt Regency, located at 5 Embarcadero Center, while the others staged the sit-in, Mehta-Neugebauer said.
The protesters were cleared out by 6:30 p.m., and no one was injured in tonight's event, she said.
The group was protesting what they say is hotel management's refusal to agree to a fair contract with more than 800 of its workers in San Francisco.
Negotiations began in August 2009, and although the two sides met earlier this month, no agreement has been reached.
"Hyatt has shown no indication that they're willing to bargain in good faith," Mehta-Neugebauer said.
The union has organized numerous boycotts, strikes and other actions during the negotiations, which Mehta-Neugebauer said has only resulted in proposals from management that would "increase the burden of health care costs on workers...and increase workloads that would jeopardize worker safety."
A Hyatt spokesman was not immediately available for comment today, but David Nadelman, general manager of the Grand Hyatt near Union Square, said last month that union leadership should try to help bring business into San Francisco rather than boycott the hotels.
"Boycotts are not good for anybody," Nadelman said. "If the boycott works, my associates don't."
The next negotiating session between the two sides is scheduled for Feb. 24, Mehta-Neugebauer said.