“The really ironic and sad fact is that the content of this opera is more relevant in 2014 than it was even in 1991, when it was premiered,” Mr. Adams said. “I think the people that are inflamed and upset about its production are people who are intent about trying to control their message. By canceling it, the Met has yielded to that intimidation.”

Mr. Adams, who praised Mr. Gelb’s support of his work and his “grit and determination” to stage “Klinghoffer,” said that he feared that without the global transmission, which is often followed by television broadcasts, many thousands of people would be deprived of the chance to see the work and make up their own minds about it.

“I’m just afraid that most people will have a sort of Wikipedia opinion about this opera,” he said. “They’ll say, ‘Oh, that’s the opera that’s been accused of anti-Semitism,’ and leave it at that. And that’s really very sad — it’s very hard when something’s been stained with an accusation like that, it’s almost impossible to wash it out.”

The work, which has a libretto by Alice Goodman, skirts the line between opera and oratorio, and is famous for its choruses of exiled Palestinians and exiled Jews. By going beyond the killing — Mr. Klinghoffer was shot to death in his wheelchair and thrown overboard — and delving into the motivations and backgrounds of its characters, including the terrorists, it drew complaints from some critics who saw it as trying to establish the equivalence of the two groups’ grievances. But it has always had champions as well: John Rockwell wrote in The New York Times in 2003 that “in the end ‘Klinghoffer’ is not anti-American or antibourgeois or anti-Semitic but prohuman.”

Mr. Adams said that he sees the murder of Leon Klinghoffer as “a tragedy of Shakespearean proportions,” and that he was dismayed by the recent Internet campaign denouncing his work as pro-terrorist and even suggesting that it was funded by “Saudi money.”

“When Klinghoffer finally sings, he sings an aria of absolute indignation,” Mr. Adams noted. “He’s being taunted and abused by this bully that the passengers called ‘Rambo,’ and he fights back. I can’t imagine anybody not identifying with his words. He says: ‘Was it your pal who shot that little girl at the airport in Rome? You would have done the same.’ Or, ‘You pour gasoline over women passengers on the bus to Tel Aviv.’ How could that be construed as making fun of the Klinghoffers?”