SHANGHAI—China has agreed to cut tariffs on American-made cars, President Trump said on Twitter, apparently signaling Beijing’s readiness to make concessions to prevent further escalating trade tensions.

Chinese officials didn’t immediately confirm or deny Mr. Trump’s assertion, with a Foreign Ministry spokesman on Monday sidestepping questions on auto tariffs.

“The two presidents instructed their economic teams to work toward the direction for removing all tariffs for win-win outcomes and mutual benefit,” Geng Shuang said, describing the outcome of weekend talks between Mr. Trump and Chinese President Xi Jinping at the G-20 Summit in Buenos Aires.

The concession would be a notable one on Beijing’s part: U.S. automobile exports to China were worth $9.5 billion last year, according to the U.S. Department of Commerce, topped only by aerospace and agriculture exports.

Three quarters of those exports came from four U.S. states: Alabama, California, Kentucky and South Carolina. Among the biggest beneficiaries if the tariffs are lifted, in addition to Ford Motor Co. and Tesla Inc.: German auto makers BMW AG and Daimler AG, which build sport-utility vehicles in the U.S. for export to China.