"I'm just here to be educated," the "Bull Durham" star said as some of the young demonstrators in the crowd asked each other, "Who is she?"
The protesters peppered her with questions about climate change, consumerism and the economy.
"It helps to focus on one thing to be accomplished," she advised.
"Is everyone here registered to vote? Are you having people sign petitions?"
Sarandon is a veteran of protest marches and civil disobedience actions for liberal and humanitarian causes.
Her latest film project is a movie about former Weather Underground militants.
The protesters she visited are staging actions against major financial institutions. A march over the weekend turned violent, with a cop pepper-spraying some demonstrators.
"I'm very happy to be here," Sarandon said. "I'm here to support freedom of speech."