U.S. Secretary of State John Kerry on Thursday warned Palestinian President Mahmud Abbas not to incite violence against Israelis, amid mounting unrest in Jerusalem.

Since the recent spate of violence began the United States has repeatedly urged both sides to show restraint, but Kerry's remarks were the first aimed explicitly at Abbas.

Israel set up checkpoints Wednesday in Palestinian neighborhoods of east Jerusalem and mobilized hundreds of soldiers as it struggled to stop attacks that have raised fears of a full-scale uprising.

Hours after the first roadblocks were erected, two more stabbing incidents occurred in Jerusalem, one outside the Old City and another near the crowded central bus station during rush hour.

Israeli artillery targeted Syrian army posts Tuesday after two rockets fired from Syria hit the Israeli-occupied sector of the Golan Heights, Israel's army said.

"In response to the rocket fire, IDF artillery targeted two military posts of the Syrian Armed Forces in the central Syrian Golan Heights," an army statement said.

Jerusalem suffered its bloodiest day yet Tuesday in a wave of unrest, with at least three Israelis killed as Palestinian attackers opened fire on a bus and drove a car into pedestrians.

The bus attack marked the first assault with a gun in Jerusalem in the two-week-old upsurge of Palestinian violence.

Prime Minister Benjamin Netanyahu vowed Monday that Israel would not bow to "knife terror" as three new stabbings in Jerusalem spread more fear among Israelis and Palestinian unrest showed little sign of slowing.

Frustrated Palestinian youths have defied President Mahmoud Abbas as well as an Israeli security crackdown by taking part in violent protests in annexed east Jerusalem and the occupied West Bank, while 18 stabbings have targeted Jews since October 3.

A Palestinian teenager was shot dead in the West Bank and four Israelis were stabbed Sunday as violence mounted following an air strike that killed a pregnant woman and toddler in Gaza.

Israeli forces shot dead the teenager, identified by the Palestinian health ministry as Ahmad Sharake, 13, during clashes near the West Bank city of Ramallah.

Israeli fire killed six Palestinians and wounded scores during clashes Friday near Gaza's border, the first unrest-related deaths there after days of violence in east Jerusalem and the West Bank, medics said.

The clashes came as Hamas' chief in Gaza called violence that has hit the occupied West Bank and annexed east Jerusalem an intifada, or uprising, and urged further unrest.

Israelis are deeply unnerved in the midst of a spate of stabbings that have brought back memories of previous Palestinian uprisings, but say they are ready to "confront" any attacker.

Those who witnessed the 1987 and 2000 intifadas especially are reverting to making mental lists of places to avoid and basic safety habits.

Arab League chief Nabil al-Arabi on Thursday condemned what he branded Israel's "racist and aggressive" practices towards the Palestinians and urged the United Nations and international community to intervene.

Arabi's statement came as clashes between Palestinian stone throwers and Israeli security forces in the occupied West Bank and annexed east Jerusalem trigger fears of a broader uprising, even a third intifada.

Israeli President Reuven Rivlin on Wednesday warned against religious incitement at a flashpoint Jerusalem holy site, saying his country and Palestinians were "sitting on a volcano."

Rivlin, whose post is mainly ceremonial, made the comments as unrest has spread in recent days, particularly in east Jerusalem and the West Bank.