It comes as Prime Minister Scott Morrison called for restraint between Israel and Palestinian militants after days of air strikes and rocket attacks.
Israeli security forces massed at Gaza’s border on Thursday and Palestinian militants pounded Israel with rockets in intense hostilities that have caused international concern.
Days of violence between Jewish Israelis and the country’s Arab minority worsened overnight, with synagogues attacked and fighting breaking out on the streets of some communities.
With concern growing the violence that flared on Monday could spiral out of control, the United States is sending an envoy, Hady Amr, to the region. But efforts to end the worst hostilities in years appear so far to have made no progress.
In renewed air strikes on Gaza, Israel struck a six-storey residential building in Gaza City that it said belonged to Hamas, the Islamist group that controls the Palestinian enclave.
At least 83 people have been killed in Gaza since violence escalated on Monday, medics said, further straining hospitals already under heavy pressure during the COVID-19 pandemic.
“We are facing Israel and COVID-19. We are in between two enemies,” said Asad Karam, 20, a construction worker, standing beside a road damaged during the air strikes. An electricity pole had collapsed by the road, with its wires severed.
In the latest Palestinian rocket attacks, one rocket crashed into a building near Tel Aviv, injuring five Israelis, police said. Sirens blared in cities across southern Israel, sending thousands running for shelters.
Seven people have been killed in Israel, its military said.
“All of Israel is under attack. It’s a very scary situation to be in,” said Margo Aronovic, a 26-year-old student, in Tel Aviv.
Israel has prepared combat troops along the Gaza border and was in “various stages of preparing ground operations”, a military spokesman said.
Health authorities in Gaza said they were investigating the deaths of several people overnight who they said may have inhaled poisonous gas. Samples were being examined and they had yet to draw any final conclusions, they said.
Meanwhile, calls are growing internationally for a de-escalation of violence in the region.
US President Joe Biden said on Wednesday that Israel has a right to defend itself, but after speaking with Prime Minister Benjamin Netanyahu, he hopes clashes with Palestinians will end quickly.
"I had a conversation with Bibi Netanyahu not too long ago," Mr Biden told reporters.
"My expectation and hope is that this will be closing down sooner than later, but Israel has a right to defend itself when you have thousands of rockets flying into your territory."
A British minister has urged Israel and Hamas to “take a step back” from the escalation.
Scott Morrison urges 'restraint'
Prime Minister Scott Morrison said it was important the conflict did not play out in Australia.
"Of course we are all very concerned about what is happening there," he told Sydney radio 2GB on Thursday.
"We have been urging restraint from all parties involved there to not take any unilateral action on those very stressful and tense situations we are finding there.
"But those things should not be played out here in Australia."
Mr Morrison restated the government's policy of a two-state solution between Israel and the Palestinians and described Australia as an agent for peace.
He urged Australians with ties to the conflict to act with tolerance and respect.
"By all means, people can have concerns and views, and there is a tolerance for that, but at the same time we do not want to import the troubles of other parts of the world into this country."
Israeli Prime Minister Benjamin Netanyahu has vowed to “continue acting to strike at the military capabilities of Hamas” and other Gaza groups. Hamas is regarded as a terrorist group by the United States and Israel.
On Wednesday, Israeli forces killed a senior Hamas commander and bombed several buildings, including high-rises and a bank, which Israel said was linked to the faction’s activities.
Hamas signalled defiance, with its leader, Ismail Haniyeh, saying: “The confrontation with the enemy is open-ended.”
Israel launched its offensive after Hamas fired rockets at Jerusalem and Tel Aviv in retaliation for Israeli police clashes with Palestinians near Al-Aqsa Mosque in East Jerusalem during the Muslim fasting month of Ramadan.
Turkey, whose hosting of Hamas leaders in Istanbul in recent years has contributed to a falling out with Israel, called on Muslim countries to show a united and clear stance over the violence.
In the fighting inside Israel, where some in the 21 per cent Arab minority have mounted violent pro-Palestinian protests, attacks by Jews on Arabs passing by in ethnically mixed areas have worsened.
One person was in a critical condition after being shot by Arabs in the Arab-Jewish town of Lod, where authorities imposed a curfew, police said.
Over 150 arrests were made overnight in Lod and Arab towns in northern Israel, police said.
Israeli President Reuven Rivlin called for an end to “this madness”.
“We are endangered by rockets that are being launched at our citizens and streets, and we are busying ourselves with a senseless civil war among ourselves,” said the president, whose role is largely ceremonial.
A number of foreign carriers have cancelled flights to Israel because of the unrest.
The fatalities in Israel include a soldier killed while patrolling the Gaza border and six civilians, including two children and an Indian worker, medical authorities said.
Gaza’s health ministry said 17 of the people killed in the enclave were children and seven were women. The Israeli military said some 400 of 1,600 rockets fired by Gaza factions had fallen short, potentially causing some Palestinian civilian casualties.
The conflict has led to the freezing of talks by Mr Netanyahu’s opponents on forming a governing coalition to unseat him after Israel’s inconclusive 23 March election.