To applause from the audience, moderator Matt Lauer repeatedly asked the warring candidates to ease up on the stinging ads that have dominated much of their campaign.
Brown, the Democrat, said he would agree to air only an ad in which he talks directly to the camera about his plans to lead the state if Whitman, the Republican, agreed to do the same.
"Let's be clear, if she takes her negative ads down ... I'll take mine off, no question. We'll do it together," he said to loud applause.
"Here's what I'll do: I will take down any ads that could even remotely be construed as a personal attack. But I don't think we can take down the ads that talk about where Governor Brown stands on the issues," she said.
Whitman said she needs to tell Californians about Brown's record as governor from 1975 to 1983 and she then proceeded to attack it.
"People need to know where I stand. And also Jerry Brown has been in politics for 40 years and there's a long track record there. And I want to make sure that people really understand what's going on here. And I'm not doing it in a mean-spirited way," she said.
Her answer prompted loud boos from the largely female audience at first lady Maria Shriver's annual women's conference. At times, the audience response drowned out the candidates.
Lauer, host of the “Today” show, moderated the conversation between the candidates and outgoing Gov. Arnold Schwarzenegger, and initially, the crowd appeared to be on Whitman's side, cheering loudly for her when she appeared.
Schwarzenegger was seated onstage between the two candidates and grinned widely during much of the sometimes awkward exchange over whether the candidates would agree to pull their negative ads. The Republican governor declined to endorse either candidate.
Lauer's call for a truce received sustained applause from the crowd, and he was forced to reiterate it after first receiving noncommittal responses.
Brown initially parsed his answer, saying that "sometimes negativity is in the eye of the beholder," but then reversed course when the crowd booed.
Whitman, a billionaire who has spent $142 million of her personal fortune on her race most of it blanketing the airwaves with TV spots first talked about the negative race without making a pledge.
"What I have found very challenging, and I'll be honest about it, are the personal attacks. The things that I have been called in this campaign it's not fair to the voters of California," she said.
That comment was likely a reference to a leaked recording of a private conversation in which a Brown campaign aide called Whitman a "whore" for allegedly cutting a pension deal with law enforcement unions to get their endorsement. The recording surfaced after Whitman struggled to overcome a scandal over her forced revelation that she had an undocumented immigrant housekeeper for nine years, who she says she fired last year when she learned about the maid’s immigration status.
Brown's campaign exploited that incident shortly afterward in an attack ad that features an image of a lie detector test.
Whitman didn't tell the truth about not voting or about how long she lived in California. She got caught in insider deals at Goldman Sachs. She changed her story about physically abusing an employee. She campaigned as tough as nails on immigration knowing her housekeeper of nine years was undocumented," it says in part.
Brown's campaign has also attacked Whitman's corporate record and her proposal eliminate the capital gains tax, which it said would "rip a hole in the state budget."
Whitman's campaign has also aggressively attacked Brown in TV ads, including some that distort his record and position on the death penalty, education reform and his records as mayor of Oakland and as governor. Whitman's campaign has used selected facts to inflate unemployment, spending and taxes during Brown's tenure.
While Whitman has vastly outspent Brown during the campaign, the Democrat has been buoyed in recent weeks by nearly $24 million in spending from union-backed independent expenditure committees, largely for negative advertising.
Brown's campaign reiterated his pledge to pull all negative ads later Tuesday, while Whitman's campaign issued a statement calling on Brown to campaign on the issues.
"Our campaign is going to continue to advertise Meg's positive vision for California, while also running fair and truthful ads that highlight Jerry Brown's long record on the issues," spokeswoman Sarah Pompei said in the statement.
After three previous debates, Tuesday's event was the candidates' last appearance together before the Nov. 2 election.
Schwarzenegger praised both candidates during the conversation but was most effusive in describing Brown's decades of public service. He also criticized Whitman for saying California can be a golden state again, saying "California IS a golden state."
Schwarzenegger and Brown later left the stage area together.
The Associated Press contributed to this article.