WASHINGTON — President Donald Trump is weighing restrictions on diesel exports as U.S. fuel prices rise, a move that could strain relations with European allies and prompt them to seek other suppliers. Options under discussion at the White House range from a 90-day export ban to narrower limits on shipments. No decision has been announced. A White House official said Trump is considering all options to lower diesel prices, which have increased from $3.74 to $6.52 a gallon over the past year. The debate comes amid oil supply disruptions tied to the Iran war and less than six weeks before the U.S. midterm elections. The oil and gas industry opposes export restrictions, warning they could make U.S. companies less competitive in overseas markets. European buyers have sharply increased their reliance on American diesel since the conflict began in February. U.S. shipments to the European Union rose by 1.5 million barrels a day in August, a 50 percent increase, according to David Jorbenaze, a senior oil analyst at commodities intelligence firm ICIS. U.S. diesel now represents about 10 percent of Europe’s consumption, S&P Global Energy estimates. Replacing those shipments could be difficult because refineries around the world are already operating at maximum capacity, Jorbenaze said. A cutoff would intensify competition for fuel from a shrinking pool of suppliers and could push prices higher, he warned. The shortage could ultimately force consumers and businesses to use less fuel, said Debnil Chowdhury, a senior fuel analyst at S&P Global Energy. That could mean Europeans driving and flying less, while households, agriculture and industry compete for available supplies. The proposal also threatens the U.S. reputation as a dependable energy supplier, according to energy experts and an outside adviser to the Trump administration. The adviser said limiting exports would raise questions about the administration’s promise to make the United States a major supplier to allies. Landon Derentz, vice president of energy and infrastructure at the Atlantic Council, said the prospect of restrictions adds to international partners’ concerns about the reliability of U.S. supplies. Ben Cahill, an energy markets director at the University of Texas at Austin, said political intervention in private fuel markets could make U.S. trade less predictable. European officials have begun discussing ways to reduce their exposure. Austrian Industry and Economy Minister Wolfgang Hattmannsdorfer said the issue underscored the need for Europe to become more independent, including by expanding ties with exporters such as Libya, Nigeria and Kazakhstan and increasing its own production. One Eastern European energy official, speaking anonymously, said European governments were losing confidence in official U.S. diplomatic channels. A second official from a mid-sized European country said its government was caught off guard by reports of a possible 90-day ban and was trying to assess the risks. A cutoff could therefore carry costs beyond the immediate fuel market: European governments may diversify their energy supplies, reducing U.S. influence in future negotiations. For American consumers, the administration’s effort to bring down domestic prices also faces a trade-off: restricting exports could shift scarce fuel into the U.S. market, but it would not by itself resolve the broader supply disruptions driving prices upward.