WASHINGTON—The U.S. turned up the heat Wednesday on China, with the Trump administration threatening to more than double proposed tariffs on imports while Congress passed a defense bill designed to restrict Beijing’s economic and military activity.

The moves come as Beijing and Washington have failed to ease an escalating trade dispute, prompting the administration to seek additional leverage. The administration, which has already affixed tariffs on billions of dollars in Chinese imports, said it would consider more than doubling...