The Public Theater announced on Thursday that it was canceling several performances of its hugely popular production of “Hamlet,” starring Oscar Isaac, saying that the show’s physical demands were becoming too much for the cast.

“As an artist-driven organization, the welfare of our actors is always a top priority,” a spokeswoman for the theater said in a statement. “Over the last few weeks the intensity that ‘Hamlet’ requires of our actors over the four-hour show is starting to take a toll.”

Theaters rarely cancel multiple performances of limited-run shows — “Hamlet” is scheduled to close Sept. 3 — and it is especially unusual for productions that have high ticket demand. Some Broadway musicals have actors alternate in roles that are physically demanding, but performances are seldom canceled.