Japanese Finance Minister Jun Azumi said from Tokyo following meetings with U.S. Treasury Secretary Timothy Geithner that tolerance with Iran was diminishing.
"We want to take concrete steps to reduce our share (of Iranian oil imports) in an orderly way as soon as possible," Azumi was quoted by Bloomberg News as saying.
Japanese oil refiner Nippon Oil & Energy Corp. is apparently in talks with producers in Saudi Arabia to compensate for any loss of Iranian crude on the market, sources told the news service.
Other Tokyo officials, however, said the government hadn't yet committed to backing away from Iran, noting talks with Saudi Arabia are just one of the country's many options.
Japan is the No. 2 importer of Iranian crude oil after China. During Geithner's tour of Asia this week, Beijing said it wouldn't restrict the amount of oil it imports from Iran.
Geithner is trying to convince Asian economies to join Western efforts against Iran. Washington and its European allies believe Iran is working to develop a nuclear weapon, though Tehran insists its intentions are peaceful.
Iran, during saber-rattling at the beginning of January, threatened to close the Strait of Hormuz, a conduit for much of the oil leaving the Middle East.