WASHINGTON—U.S. and Chinese trade negotiators failed to break an impasse following two days of globally watched trade talks, as both sides tried to prevent sentiment from deteriorating further.

In tweets Friday afternoon, President Trump said newly imposed 25% U.S. tariffs on $200 billion in Chinese imports would remain in place pending future negotiations. But he called the talks “candid and constructive” and said his relationship with Chinese President Xi Jinping “remains a very strong one and conversations into the future...