A city in eastern China’s Jiangsu province suspended site selection Aug. 10 for a $15 billion Sino-French nuclear waste recycling project after thousands of residents protested during the weekend.

Lianyungang, a city of more than 4.5 million people, earlier called the protests illegal and urged residents not to organize or gather without police approval, according to a statement on the government’s Weibo account. Hours later, officials issued another statement, saying they suspended site selection work on the project between China...