President Donald Trump’s chief economic adviser, Gary Cohn, emphasized to foreign climate and energy officials Sept. 18 that the U.S. still intends to withdraw from the Paris climate accord, three people familiar with his remarks at a private breakfast said.

Speculation that Trump would reverse course and remain in the Paris deal was heightened after the European Union’s climate chief, Miguel Arias Canete, said Sept. 16 in an interview that the U.S. had signaled it wants to seek new terms...