The cost to attend the luncheon at Shady Canyon, a gated community in Irvine, was $1,000, with an additional $1,500 to attend a photo reception with the former Massachusetts governor.
Romney's presidential fundraising operation dwarfs those of his GOP rivals, with more than $75 million already in donations.
Sixty to 70 protesters assembled at the Century Plaza Hotel in Century City. Among them were Democratic elected and party officials and labor leaders who planned a news conference regarding Romney's positions on immigration. A protest outside the hotel was also planned by activists from labor unions, Occupy LA and immigration rights supporters.
Romney began his two-day visit to California on Monday with a speech in San Diego at NuVasive, a maker of spinal care devices, criticizing the national health care law championed by President Barack Obama.
Romney, who has a has a home in La Jolla, said companies like NuVasive are important because they sell products around the world and keep our economy competitive. He said their progress is threatened by the Obama administration.
"(I'm) absolutely convinced that it's time to replace the president with somebody who understands what it takes to get good jobs and rising economy and I intend to do that," Romney said.
Romney was scheduled to appear on NBC's "The Tonight Show with Jay Leno" on Monday, his first time on a late-night talk show since announcing his 2012 presidential candidacy.
Romney's West Coast trip has been marred by protests and theft. A briefcase, two iPads, two handheld radios and two laptops were taken from the SUV of a Romney aide in a San Diego parking garage. The belongings contained detailed information about Romney's presidential campaign.
The Associated Press and City News Service contributed to this report.