TOKYO—Japan, under intensifying pressure to join sanctions proposed by the U.S. and Europe, is bracing for the possibility of curbing its imports of Iranian oil, with some refiners seeking other sources.

A Japanese government official said Thursday the country will likely have to reduce imports from Iran substantially, though it hopes to avoid an embargo that would completely cut off the country that provided 8.8% of Japan's crude-oil imports over the first 11 months of 2011.

Meanwhile, an executive of Japan's petroleum association said refiners are already looking for oil to replace some of what the country now buys from Iran.

"We may utilize oil inventories from Saudi Arabia or Abu Dhabi," Yasushi Kimura, vice president of the Petroleum Association of Japan, told reporters at an annual New Year's reception in Tokyo. "We are considering various scenarios."

In addition to forcing Japan to find other sources of oil, analysts say, the loss of the Iranian supply will likely drive up prices—a chilling prospect for Japan, already grappling with rising fuel costs.