"We condemn bigotry and hate speech in every form," Common Cause said in a statement.
The comments were made during interviews by videographer Christian Hartsock, who co-produced the undercover footage of ACORN staffers that embarrassed the community organizing group and caused a political firestorm.
The interviews were posted on YouTube and created a stir in the blogosphere. In the video, Hartsock is heard laughing as he goads his subjects with questions like, "After we impeach Clarence Thomas, what do we do with him?"
One white woman suggests the black Supreme Court justice should be lynched, while a white man says, "Put him back in the fields." No one interviewed by Hartsock was identified, and it's not clear if they knew who they were talking to.
The rally was held Sunday after a panel discussion hosted by Common Cause called "Uncloaking the Kochs." It took place near the site of a four-day meeting of wealthy conservative political activists organized by brothers David and Charles Koch of Wichita-Kan.-based Koch Industries, one of the nation's largest privately held companies.
According to the Common Cause statement, the panel discussion's intent was "to call public attention to the political power of Koch Industries and other corporations."
The brothers have held similar conclaves in the Palm Springs area and Aspen, Colo., for years, but this conference was met with increased scrutiny. Liberal groups have targeted the brothers for criticism because of their funding of the fight against global warming laws and their financial support of Americans for Prosperity, an organization that has worked closely with tea party groups.
Sunday's demonstration outside the Rancho Las Palmas resort was mostly peaceful, but 25 people were arrested for trespassing. They were arrested without incident, booked and released, authorities said.
Hartsock has contributed to conservative columnist Andrew Breitbart's website biggovernment.com. He also co-produced the ACORN videos, in which staffers offer advice to a woman and man posing as a prostitute and pimp. The videos were posted on Breitbart's site.