"I'm an enormous admirer of Dan and what he has accomplished in Quicken Loans. Yahoo is not the type of thing I'd ever be an equity partner in. I don't know the business and wouldn't know how to evaluate it, but if Dan needed financing, with proper terms and protections, we would be a possible financing help," Buffett told CNBC.
Berkshire previously provided financing to investment firm 3G Capital for its takeovers of Heinz and Kraft. Berkshire was also an equity partner in that transaction, and remains a major equity partner in Kraft Heinz.
The Yahoo deal would be different, as Berkshire would only putting up financing if it's secured.
Reuters first reported on Friday that Buffett would consider helping finance Gilbert's offer for Yahoo. Gilbert is the chairman of Quicken Loans and the owner of the National Basketball Association's Cleveland Cavaliers. Former senior Yahoo executives Dan Rosensweig and Tim Cadogan have been advising Gilbert, according to Recode.
The process of selling the struggling internet firm is in its second round. Verizon Communications, which acquired AOL last year for $4.4 billion, is among the other bidders.
Earlier this month, AOL CEO Tim Armstrong told CNBC: "It makes sense to look at [Yahoo]."
Private-equity giant TPG Capital and a group that comprises rival PE firms Bain Capital and Vista Equity Partners, are also in the running for Yahoo, according to The New York Times. In the Bain-Vista bid, former senior Yahoo executives — including Ross Levinsohn, Bill Wise, and Ken Fuchs — are involved in the process, Recode reported.
In February, Yahoo CEO Marissa Mayer announced the company would auction off its internet business and cut 15 percent of its workforce. The company is also selling $1 billion to $3 billion in noncore assets, such as patents and property.
Former Yahoo president and CFO Susan Decker, who joined Berkshire in 2007, told CNBC last month that Yahoo has spread itself too thin. "Because of the breadth of what Yahoo does, they sort of became mediocre in so many properties." Decker said. "Yahoo would benefit from going private or becoming part of a larger corporation."
Buffett and Gilbert have been close friends since 2012, when Gilbert joined the Giving Pledge — an initiative created by Buffett and Microsoftco-founder Bill Gates to encourage billionaires to give away at least half of their wealth.
Berkshire provided insurance on the $1 billion prize offered by Quicken Loans to anyone who completed a perfect March Madness bracket in the 2014 National Collegiate Athletic Association men's basketball tournament. No one pulled off the feat.
Buffett told CNBC on the Monday after Berkshire's April 30 annual shareholders meeting that Yahoo Finance did a "terrific job" live streaming what's been described as the Woodstock of capitalism in Omaha Nebraska. This year was the first time Berkshire allowed the meeting to be streamed on the internet.
— Reuters contributed to this report.