Mr. Zafrani, whose film has played dozens of festivals in the United States and abroad and deals with the lives of disabled children at a center near Tel Aviv, said he put news of the rejection, and its reasoning, on his Facebook page without identifying the festival or Mr. Magnussen.

“Many people wrote me saying, ‘Let’s send emails, let’s shame him,’ ” he said in an interview. “But I don’t want to hurt anyone, and I don’t think it’s just this guy. I think the larger issue is that there is a boycott — which I can understand and not understand; I’m not political. But I think we should suspend it for some things. Arts. And sports: I just saw an Israeli guy who competed in the disabled Olympics against an Iranian guy, and they were hugging. You don’t see this in any other place.”

Mr. Magnussen did not respond to phone messages and emails, but over the weekend he said on Facebook that he signed a petition supporting the boycott three years ago; is opposed to Israeli policies toward Palestinians; and that although his decision was not about an individual filmmaker or film, the aims of the boycott are sound.

Yet he may have slightly misinterpreted the boycott’s mission: According to Omar Barghouti, a Palestinian activist and a founder of the Boycott, Divestment and Sanctions (or, B.D.S.) movement, the cultural and academic part of the campaign calls for “boycotts against Israeli institutions that are complicit in Israel’s violations of international law, not against individuals.”

Image Roy Zafrani Credit... Gadi

Mr. Barghouti said by email that although he wasn’t familiar with Mr. Magnussen’s reasoning, the cultural boycott guidelines “unambiguously” state that “mere affiliation of Israeli cultural workers to an Israeli cultural institution is therefore not grounds for applying the boycott.” He added, “If, however, an individual is representing the State of Israel or a complicit Israeli institution, or is commissioned/recruited to participate in Israel’s efforts to ‘rebrand’ itself, then her/his activities are subject to the institutional boycott the B.D.S. movement is calling for.”