WASHINGTON—The U.S. decided to hold off on implementing a major new sanctions push against North Korea while it looks to revive a summit between President Donald Trump and North Korean leader Kim Jong Un next month.

The White House was prepared to announce the ramped-up sanctions regime as soon as Tuesday but decided Monday to indefinitely delay the measures while talks with North Korea proceed, a U.S. official said, citing progress in efforts to repair diplomatic relations between Washington and Pyongyang.

U.S....