Warner Bros. Discovery Inc. Chief Executive David Zaslav told employees that he wants CNN to focus on maximizing its impact, not profitability, and set itself apart from a cable-news industry that he said is dominated by “advocacy networks.”

In an hourlong interview Thursday with Oprah Winfrey at a theater on the Warner Bros. lot in Burbank, Calif., that was streamed to employees around the globe, Mr. Zaslav laid out his vision for the company, which he started leading days ago after AT&T Inc. spun off its WarnerMedia unit and Discovery merged with it. The merger created a media giant whose properties include the Warner Bros. movie studio and the cable channels HBO, CNN, TNT, Food Network and HGTV.