WASHINGTON—Donald Trump and Vladimir Putin discussed two thorny topics—Venezuela and North Korea—in a more than hourlong phone call Friday, but the U.S. president didn’t press his Russian counterpart on another sensitive subject: Moscow’s meddling in the American political system.

The conversation is the first known interaction between the two leaders since the Justice Department released special counsel Robert Mueller’s report, which detailed more than nearly 200 pages of Russia’s elaborate efforts to interfere in the 2016...