Israeli police clashed with Palestinian protesters in Jerusalem as thousands of people converged on a cemetery for the burial of an Arab teenager, who Palestinians say was killed by Israeli extremists in a suspected revenge attack.

Palestinian militants fired at least six rockets and mortar shells toward Israel, but that was a sharp decline from recent weeks and no retaliatory Israeli airstrikes were reported a day after the Israeli military rushed additional forces to its southern border with the Gaza Strip because of intensifying barrages.

An ambulance carried the body of 16-year-old Mohammed Abu Khdeir, wrapped in a Palestinian flag and traditional headscarf, to a mosque in the neighbourhood where he lived. Then mourners carried the open casket through the crowd to a cemetery.

During the procession, masked Palestinians threw rocks at Israeli police officers on duty nearby who responded with stun grenades. More than 2,000 people attended the funeral.

Police had beefed up security in and around Jerusalem as the funeral coincided with the first Friday prayer services of the Muslim fasting month of Ramadan, and no casualties were immediately reported from the clashes or other unrest in the area.

Police clashed with hundreds of Palestinians in Ras al-Amud and Wadi Joz in the eastern sector of the city, which has been rocked by violent protests since Abu Khdeir's burned body was found in a forest after he was seized near his home in the east Jerusalem of Shuafat.

Tensions have been high since three Israeli teenagers were abducted in the West Bank on June 12, sparking a massive manhunt that ended with the discovery of their bodies early this week.

Israel has blamed Hamas for the abductions and launched a crackdown on the Islamic militant group in the West Bank, drawing rocket attacks out of Gaza and Israeli airstrikes in a near-daily cycle of retaliation. Hamas, which has kidnapped Israelis in the past, praised the kidnapping of the teens but did not take responsibility for it.

Palestinians have accused Israeli extremists for killing Abu Khdeir, saying it was a revenge attack for the deaths of the three Israeli teens. Israeli police said an investigation was ongoing and the motive has yet to be determined.

On Thursday it was announced by the Israeli military that reinforcements had been sent to the border with Gaza in a bid to halt a growing wave of rocket fire. But it was insisted that the move was "defensive".

The killing of the Palestinian boy was widely condemned by Israeli leaders, including prime minister Benjamin Netanyahu who has vowed to find the attackers.

"We don't know yet the motives or the identities of the perpetrators, but we will. We will bring to justice the criminals responsible for this despicable crime whoever they may be," Netanyahu said. "Murder, riots, incitement, vigilantism, they have no place in our democracy."

On Friday Palestinian militants fired at least six rockets and mortars at Israel, two of which exploded prematurely inside Gaza, the military said. But that was far fewer than the dozens of barrages reported in previous days and the border area was relatively calm.

The military says Palestinian militants have fired some 140 rockets at southern Israel in recent weeks. The air force responded with airstrikes on about 70 targets in Gaza, the military said.

Abu Khdeir's family set up a large tent outside the home for those seeking to pay condolences and distributed posters mourning his death.

Mourners chanted "with our soul, with our blood, we would sacrifice anything for you (Palestine)" and "Allahu akbar!" or "God is great".

Waving a Palestinian flag and with a traditional scarf covering his face at the funeral, Shuafat resident Rami, 20, said he came to chant and mourn his neighborhood friend Mohammed. "Frankly, my emotions cannot be described. I am happy and sad. I am happy because he died a martyr, but I am sad because they kidnapped him, killed him and then burned him."

Protests broke out in a few areas after Muslim prayers, police said. Hundreds of Palestinians threw rocks at police who responded with stun grenades.

Palestinians also threw rocks at the most sensitive holy site in Jerusalem. The hilltop compound is revered by Jews as the Temple Mount, where the two biblical Jewish Temples stood. It is sacred to Muslims as the Haram as-Sharif, or Noble Sanctuary, marking the place where they believe the Prophet Muhammad ascended to heaven.

On the main road in Shuafat, streets and light rail tracks remained covered in charred debris, rocks and large garbage cans.