Israeli security forces temporarily sealed off one of Islam’s holiest sites Thursday in a rare move that reflected soaring tensions after a suspected Palestinian gunman tried to assassinate an ­American-Israeli activist who advocates greater Jewish access to the contested religious ground.

Israeli authorities said later Thursday that they would reopen the Jerusalem site Friday morning.

Jerusalem police were on high alert Thursday as riot squads flooded into the Old City to block routes to the Dome of the Rock and al-Aqsa mosque, the third-holiest place in Islam. The blanket security measures at the site — the most stringent in decades — brought strong denunciations from the Palestinian president, Mahmoud Abbas, who compared the closure to “a declaration of war.”

In the past, disputes at the site have touched off Palestinian riots and prolonged uprisings. Palestinian activists called Thursday for a “day of rage” on Friday in Jerusalem, despite the Israeli promise to reopen the gates to al-Aqsa. Men under age 50 will be barred, however.

The current tensions also could overshadow talks scheduled later in Washington between a high-level Israeli delegation and national security adviser Susan E. Rice. The meeting was called after a report that an Obama administration official used derogatory language to describe Israel’s prime minister, Benjamin Netanyahu, as a coward.

Israeli right wing activists confront a security official near the Western Wall inside the old city of Jerusalem. (Finbarr O'reilly/Reuters)

The events in Jerusalem began late Wednesday when a gunman on a motorcycle wounded activist Yehuda Glick, 48, who has been pressing authorities to insist that Jews be allowed to pray at the Temple Mount. It is the holiest site in Judaism, and it includes the Muslim holy sites.

On Thursday, an Israeli counterterrorism unit killed the suspected gunman following a shoot­out in a Jerusalem neighborhood, police said.

Glick was wounded as he emerged from a conference of activists and right-wing Israeli politicians who want to pray at the walled esplanade, known to Jews as the Temple Mount and to Muslims as the Noble Sanctuary.

In the aftermath of the shooting, Israeli authorities took the highly unusual step of denying access to all but the Muslim caretakers.

Jews and Christians are normally allowed to visit the site as tourists. But they are banned from praying, singing and making religious displays.

The first and second Jewish temples — historically the center of Jewish life — were located on the same spot. Romans destroyed the second temple in A.D. 70. Jews now pray at the Western Wall, the ramparts close to the site.

In Jordan, which has oversight of Muslim holy sites in Jerusalem, Islamic Affairs Minister Hayel Daoud called the closure “state terrorism,” the state-run Petra news agency reported.

The Palestinian man suspected of shooting Glick was found early Thursday in the Abu Tor neighborhood. An Israeli counterterrorism unit came under fire and killed the suspect in a gun battle, according to Micky Rosenfeld, spokesman for the Israeli police.

The Shin Bet domestic intelligence agency identified the suspect as Muatnaz Hijazi, 32, who worked in the restaurant at the Begin Center, where Glick attended the meeting.

“The attack was clearly planned ahead of time,” Rosenfeld said.

Israeli authorities said that Hijazi had served time in an Israeli prison for “security offenses,” but did not offer details. The intelligence agency said that Hijazi was once a member of Islamic Jihad, branded a terrorist group by Israel.

Glick’s father, Shimon, said in an interview that his son was in critical but stable condition.

“We know this is going to be a long process to recovery,” said Glick, who is physician. “He has several wounds in the bowel and has had a piece of lung cut out. He is heavily sedated.”

The father said he did not know whether Glick was the intended target. “He stands out in the crowd because he is tall and he has red hair. I don’t know why they picked him, but maybe because he is very obvious. He stands out like a red flag in front of a bull,” he said.

Glick is the well-known leader of HaLiba, a group dedicated to “reaching complete and comprehensive freedom and civil rights for Jews on the Temple Mount.”

A number of right-wing Israeli politicians, including members of Netanyahu’s coalition government, have also pressed for the right of Jews to pray on the mount.

Glick was formerly a director at the Temple Institute, which is dedicated to preparing for and building a third temple on the mount, with a return of animal sacrifice, as was the custom 2,000 years ago.

Glick has been banned by police from the Temple Mount in the past because of his advocacy, which is seen as highly provocative by Muslims and many Israelis.

While Glick and other activists say they are seeking equal rights to pray on the mount, many Muslims distrust their motives and fear some Israelis want to change the status quo agreements for the site.

“This is not incitement,” Rabbi Chaim Richman, a director of the Temple Institute, said in an interview last year. “Our mission is to kindle the spark of desire for the time when Jews are a light unto the world, and Muslims will agree it is time to rebuild, and all nations of the world will come to the Jews and ask them to rebuild.”