A former attorney general of America, a member of Congress and another of the Knesset joined hundreds of New Yorkers and school children for a protest against plans of the Metropolitan Opera to stage “The Death of Klinghoffer.”

Waving signs that said “Don’t Give Hate a Voice” and shouting “shame on the Met,” protestors rallied for two hours at Dante Park, across Seventh Avenue from the Met. At least a dozen speakers stirred a crowd that was aghast that the Met would be stage a work about the 1985 slaying by Palestinian Arab terrorists of New Yorker Leon Klinghoffer.

The protest took place as patrons of the Met were arriving for the season’s opening. The protesters’ immediate aim was the cancellation of the Klinghoffer opera, which is set to open next month. The opera was composed a generation ago by John Adams, with a libretto by Alice Goodman. More broadly the aim of the protestors — organized by Americans for a Safe Israel, the Simon Wiesenthal Center, and more than 20 other groups — appeared to be marking the contrast with more establishment Jewish organizations, who failed to participate in the protest. These included such institutions as the Anti-Defamation League, the American Jewish Committee, and the United Jewish Appeal.

Although Klinghoffer was a New Yorker, Mayor de Blasio failed to show, as did Senators Schumer and Gillibrand. The absent of such major figures seemed only to fire up the crowd, who heard Judge Michael Mukasey, who’d been attorney general under President George W. Bush, predict that the “moral bankruptcy of the Met” would be followed “by the financial bankruptcy of the Met.”

The general was marking the point that the Met’s new general manager, Peter Gelb, took over the Met at a time of financial crisis and was trying to move it forward with new material. Mr. Gelb has said repeatedly that he doesn’t believe “Klinghoffer” to be anti-Semitic or that it glorifies terrorism. Mr. Mukasey, referring to efforts to take an open-minded view of the opera, quoted the late mayor Ed Koch as saying a person can be “so open minded that your brains fall out.”

Among the speakers was Debra Burlingame, who emerged as voice in the city after 9/11. Her brother, Charles, had been the pilot of the American Airlines Flight 77 that terrorists flew into the Pentagon. She told the crowd that she could not imagine what it must be like for Leon Klinghoffer’s daughters to have to wake up every day knowing that somewhere in the world an opera was being staged honoring their father’s killers.

A message was read at the protest from Judah Pearl, the father of the American newspaperman Daniel Pearl, who was captured in Pakistan and slain by terroists after stating, “I am an American Jew.” His father said he hoped Pearl’s last words would strengthen the hearts of the protesters. Rabbi Avi Weiss of Riverdale spoke of God’s admonishment of Cain, “thy brother’s blood crieth unto me . .”

Remarks were also made by Congressman Eliot Engel of the Bronx and a member of the Knessett, Nissim Zeev, a member of the Israeli religion political party Shas. Actor Tony Lo Bianco gave a devastating riposte to those who sought to justify the staging of the opera on the grounds of free speech. “Freedom of expression is your right,” he said, “but the enemy can hear you.”