WASHINGTON—President Trump said Sunday he would delay an increase in tariffs on Chinese goods set to take effect at the end of this week, citing “substantial progress” on issues including intellectual property and technology transfer after a weekend of talks.

In a tweet, Mr. Trump wrote that should progress continue, the U.S. would plan a summit with President Xi Jinping of China to “conclude an agreement” that would settle a yearlong trade fight between the two nations.

Mr....