China will exempt purchases of U.S. soybeans, pork and other agricultural products from punitive tariffs, in a move that appears aimed at addressing one of President Trump’s most pressing demands during the protracted trade war.

China’s official Xinhua News Agency said the government would support purchases of U.S. agricultural products by Chinese companies and waive the tariffs Beijing has imposed as trade tensions have intensified. The report didn’t specify the amount of products affected by the measure, which was attributed...