PARIS — On a recent afternoon, Karidja Touré stood under the gilded arch of the Théâtre du Châtelet’s stage, and listened intently while the rapper and writer Abd al Malik asked her to add some fear to her voice and more agitation to her gestures.

Other cast members for the theater’s upcoming production of Albert Camus’s “The Just Assassins” watched from the wings or from seats in the auditorium.

“We want to see you panic,” Malik told Ms. Touré. “This is a life-or-death situation.”

It was a typical rehearsal that could have played out in any theater, anywhere in France. But one thing stood out: The ethnic diversity of the artists.