Updated

Israeli security forces braced themselves for more unrest Friday after days of Palestinian attacks that spread this week from beyond the flashpoint of violence at Jerusalem's holiest site and across the West Bank to Israeli cities.

Israeli police barred young Muslim men from the sacred Jerusalem site as a measure to ensure calm on Friday morning.

Spokeswoman Luba Samri said men under 45 are barred from the Al-Aqsa mosque compound while women of all ages can enter.

The age limit has been set intermittently in an attempt to ensure peace at the site, as it's mostly younger Palestinians involved in the violence.

Samri said police are on high alert.

The unrest began about three weeks ago as Palestinians repeatedly barricaded themselves inside the Al-Aqsa mosque and hurled rocks and firebombs at police.

It was fueled by Palestinian allegations that Israel plans to change the delicate arrangement at the hilltop compound, holy to Jews and Muslims. Israel has adamantly denied the allegations and accused Palestinian leaders of incitement.

The attacks were initially confined to east Jerusalem, site of the sacred compound, and the West Bank — both territories captured by Israel from Jordan in the 1967 war and claimed by the Palestinians for their future state. But this past week the violence has spread to Tel Aviv, Afula and other Israeli cities.

What began as Palestinians throwing rocks and firebombs at passing cars and police morphed into a deadly shooting and a rash of knife attacks where Palestinians stabbed Israeli civilians and soldiers in the streets.

The attacks have shocked Israelis and sparked fears of a new Palestinian Intifada, or uprising. However Israeli officials have downplayed that possibility, saying this is the kind of violent spike Israel has faced periodically in recent decades.

Prime Minister Benjamin Netanyahu has called the attacks a "terror wave."

Israel has significantly beefed up security in response to the violence in Jerusalem, and on Thursday police set up metal detectors at the entrance to Israel's Old City.

The hilltop compound is a frequent flashpoint and its fate is a core issue at the heart of the Israeli-Palestinian conflict. It is known to Jews as the Temple Mount, site of the two biblical Jewish temples. Muslims revere it as the Noble Sanctuary, where they believe the Prophet Muhammad ascended to heaven.

Non-Muslim visitors are only allowed to enter the site at specific hours and are banned by police from praying there. Many Muslims view these visits as a provocation and accuse Jewish extremists of plotting to take over the site. Israel has promised to ensure the delicate arrangement at the site and insists it will not allow the status quo there to be changed.

But Palestinians say that in the last two months, there has been a new development where Israel has intermittently restricted some Muslims from the compound when Jews visit. Israel says this is to reduce friction, but Palestinians claim that Israel intends to establish Muslim-free Jewish visiting hours. The site is so sensitive that even rumors are enough to trigger violence there.