In an interview on Fox Business Network, Buffett said, "we sold based on price," adding that "it was 100 percent a decision based on valuation."
He also said he probably sold too soon because shares of PetroChina have risen since the sales began.
Berkshire once owned more than 11 percent of the Chinese oil company's publicly floated shares.
The shares were worth $3.31 billion at the end of 2006, well above the $488 million that Berkshire paid for them, according to Berkshire's latest annual report. Berkshire's selling first surfaced in July.
Critics have said PetroChina, through its government-owned parent China National Petroleum Corp, is too closely linked to Sudan. The Sudanese government has been blamed for what the White House has called genocide in the Darfur region.
Shareholders at Omaha, Nebraska-based Berkshire's annual meeting in May overwhelmingly defeated a proposal calling on Berkshire to divest its PetroChina stake.
Buffett had opposed the proposal, though he said conditions in Darfur were deplorable and that he sympathized with people who wanted to change them. He said selling would not improve conditions in Sudan, and that Berkshire should not divest automatically because it disagrees with a particular activity.
Separately, Buffett denied rumors that Berkshire might buy a stake in Bear Stearns Cos (NYSE:BSC - News). The investment bank has this year suffered the collapse of two hedge funds and asset write-downs, helping push its shares down 27 percent.
An article last month in the New York Times said investors including Buffett may buy part of Bear Stearns. This month, Bear Stearns Chief Executive James Cayne said he would consider selling a stake to an investor from China or the Middle East.
In Thursday's interview, Buffett said he has not bought shares of mortgage lender Countrywide Financial Corp (NYSE:CFC - News) or luxury homebuilder Hovnanian Enterprises Inc (NYSE:HOV - News), shares of which are down 61 percent and 70 percent respectively this year.
He identified the Brazilian real as the currency Berkshire owned in May, when Buffett told shareholders he had a stake in one "surprise" currency.
Berkshire Class A shares closed down $995 at $129,000 on Thursday. The company's market value is about $199 billion.
