* Conflict erupted on Monday, still no sign of end
* U.S. and Arab diplomats pushing to restore calm
* Israel strike destroys 12-storey building in Gaza
* Rocket salvoes from Gaza strike Tel Aviv suburb (Adds U.S. reaction, pro-Gaza protests in Europe)
By Nidal al-Mughrabi and Rami Ayyub
GAZA/JERUSALEM, May 15 (Reuters) - Israel pounded Gaza, destroying a tower block that housed media organisations and which it said had militant assets, while Palestinian rocket salvoes hit Tel Aviv on Saturday, with no sign of an end to almost a week of fighting.
The death toll is rising from the worst escalation since 2014 and diplomacy has so far failed to quell it.
Israel's military brought down a 12-storey block in Gaza City that housed the U.S. Associated Press and Qatar-based Al Jazeera media operations, as well as other offices and apartments, leaving a huge heap of broken masonry.
Israel gave advance warning of the strike so it could be evacuated and said later the building contained military assets of Hamas, the Islamist group that runs Gaza.
The United States told Israel "that ensuring the safety and security of journalists and independent media is a paramount responsibility," White House Press Secretary Jen Psaki said.
The AP and Al Jazeera strongly condemned the attack.
Palestinians say at least 139 people, including 39 children, have been killed in Gaza since the conflict erupted on Monday.
Israel has reported 10 dead, including two children.
In Tel Aviv, residents fled for cover amid wailing sirens as Hamas militants fired barrages of rockets. One hit a residential block in the Ramat Gan suburb, killing a 50-year old man, medics said.
The group said the salvoes responded to overnight strikes on Gaza's Beach refugee camp, where a woman and four of her children were killed when her house was hit. Five others died, medics said. Israel said it targeted an apartment used by Hamas.
Hamas began its assault on Monday after tensions over a court case to evict several Palestinian families in East Jerusalem and in retaliation for Israeli police clashes with Palestinians near the city's al-Aqsa Mosque, Islam's third holiest site.
Israel's bombardments have sent columns of smoke above Gaza City and lit up the enclave's night sky.
Akram Farouq, 36, dashed out of his home overnight with his family after a neighbour told him they had received a call from an Israeli officer saying their building would be hit - a familiar pattern for attacks on what Israel deems military sites.
"We haven't slept all night because of the explosions, and now I am out in the street with my wife and children, who are weeping and trembling," Farouq said.
Living conditions for Gaza's 2 million people are worsening, with households receiving just four hours a day of power instead of the usual 12, Palestinian officials said.
Israelis have learned to dive for cover at any time of the night and day. In Israel's coastal city of Ashdod, Mark Reidman surveyed damage to his apartment building from a rocket hit.
"We want to live in peace and quiet," the 36-year-old said, adding he had to try to explain to his three young children "what happened, and why this is happening".
Regional and international diplomatic efforts have yet to show any signs of halting hostilities.
U.S. President Joe Biden's envoy Hady Amr, deputy assistant secretary for Israel and Palestinian affairs, arrived in Israel on Friday, before a meeting on Sunday of the U.N. Security Council. The U.S. Embassy said in a statement that the envoy aimed "to reinforce the need to work toward a sustainable calm".
Egypt, which shares a border with Gaza and has led regional diplomatic efforts, has been pushing for a ceasefire so talks could start, two Egyptian security sources said on Friday.
There have been protests in support of Palestinians in the Middle East, Europe and Australia. In France, police used tear gas and water canon to disperse demonstrators who defied a ban in Paris on Saturday, but authorised protests were held elsewhere. Hundreds turned out in Madrid.
In Israel, the conflict has been accompanied by violence among the country's mixed communities of Jews and Arabs. Synagogues have been attacked, Arab-owned shops vandalised and street fights have broken out. Israel's president, who has a largely ceremonial role, has warned of civil war.
Palestinians, who each year on May 15 mark "Nakba" or Catastrophe Day, their displacement in the 1948-49 war that accompanied the creation of the modern state of Israel, clashed with police across the occupied West Bank on Saturday.
Medics reported 29 Palestinians injured, 17 of them by live fire. Medics previously reported 11 people killed on Friday in the West Bank.
The conflict adds complexity to Israel's fractious politics. It has dealt a blow to opposition attempts to unseat Prime Minister Benjamin Netanyahu, when a potential right-wing partner scrapped coalition talks after violence erupted. This may mean Israelis face a fifth election in just over two years.
Israel said on Saturday about 2,300 rockets had been fired from Gaza at Israel since Monday, with about 1,000 intercepted by missile defences and 380 falling into the Gaza Strip.
(Additional reporting by Dan Williams, Stephen Farrell and Ari Rabinovitch in Israel, Ali Sawafta in Ramallah, Aidan Lewis in Cairo, Nandita Bose in Washington Writing by Rami Ayyub and Edmund Blair Editing by Frances Kerry)
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