"There were Palestinian worshippers who turned up for morning prayers. They were told by the police force that anyone under the age of 50 would not be allowed through," Al Jazeera's Sherine Tadros, reporting from Jerusalem, said.
"There are [at present] about 7,000 Jewish worshippers attending a prayer, a blessing at the Wailing [Western] Wall, which is just at the foot of the Haram al-Sharif.
"This is one of the three times during the year in which Jewish worshippers are told to go to Jerusalem and pray."
Justifying the restrictions on entry to the mosque, Micky Rosenfeld, an Israeli police spokesman, said: "These measures were taken to avert new incidents on the compound and the Old City and to prevent stones being thrown at the Jewish faithful who come to pray at the Western Wall."
He said "hostile elements are inciting to violence", pointing the finger at the Islamic Movement, an Arab-Israeli group that regularly calls the faithful to rally to the defence of al-Aqsa.
For its part, the Palestinian Authority urged the international community to "immediately intervene and bring the question of the al-Aqsa mosque before the UN Security Council".
Jordan, meanwhile, summoned Israel's ambassador in Amman to demand a halt to "repeated violations" by Israel at the al-Aqsa compound.
Skirmishes broke out near the Lion's Gate entrance to the Old City on Sunday after Israeli security forces closed off Haram al-Sharif to prevent Palestinians from joining about 200 worshippers who had staged a sit-in at the site.
The Palestinians had gathered at the mosque on Saturday night, saying they intended to prevent Jewish hardliners from gaining access.
The Palestinian group Hamas, which effectively governs the Gaza Strip, has warned that an "aggressive assault" by Jewish worshippers on the compound risks sparking a new wave of unrest in Israel and the Palestinian territories.
"... we will not sit on our hands as we will rise in defence of our sanctities. Prejudice to al-Aqsa Mosque is not only a red line, but it is a ticking time bomb that will explode in the face of the Zionist aggressors," Hamas said in a statement.
'Flock to al-Aqsa'
Hamas also urged Palestinians to "flock to al-Aqsa" to offer their prayers in defiance of the Israeli blockade.
"We call on the brave fellow Palestinians and all the Arab and Muslim peoples to rise in defence of our sanctities, to spark another Intifada [uprising] to defend Jerusalem and al-Aqsa mosque," the group's statement said.
At least 13 Palestinians were injured and seven detained in clashes the previous Sunday after a group of non-Muslims entered the mosque compound.
Israeli police said the group was made up of French tourists, while the Palestinians said they were Israeli extremists.
Israel captured and annexed the Old City with its holy sites, along with the rest of Arab East Jerusalem and the West Bank, in the war of 1967.