“Israel,” she said, “was created exactly 70 years ago as a haven for refugees from the Holocaust. But the mistreatment of those suffering from today’s atrocities is simply not in line with my Jewish values. Because I care about Israel, I must stand up against violence, corruption, inequality, and abuse of power.”

Israel has drawn international censure for using live fire against mostly unarmed protesters during recent weekly demonstrations along the fence dividing Gaza from Israel.

The protest, which began as a grass-roots campaign and was quickly adopted by Hamas, the Islamist militant group that controls Gaza, is meant to draw international attention to the 11-year blockade of the isolated, impoverished coastal territory, which Israel and Egypt impose, citing security grounds, and to Palestinian demands for a return to lands in what is now Israel.

Israel’s military says it is acting to prevent any mass crossing of the fence and to prevent attacks against Israeli soldiers and nearby communities under cover of the protests.

Ms. Portman’s decision was not the first time a celebrity has opted out of an event in Israel over disagreements with its policies. Also this year, the musician Lorde ignited outrage in some quarters when she canceled a concert in Tel Aviv at the urging of fans who asked her to reconsider the performance.

Her cancellation drew angry denunciations from several prominent Israelis and Jewish leaders. A well-known American rabbi, Shmuley Boteach, took out a full-page ad in The Washington Post calling her a bigot, and an Israeli rights group filed a lawsuit against two New Zealanders who wrote one of many open letters urging Lorde to cancel the show.

Many others offered support to the singer, including dozens of celebrities and artists who signed an open letter in The Guardian. Among them were the former Pink Floyd frontman Roger Waters, the singer Peter Gabriel, and the actors Viggo Mortensen and Mark Ruffalo. Hundreds of other celebrities criticized Israel and offered their support for the Palestinian cause, including Rihanna, Penélope Cruz and Russell Brand.