The safety of Australians in the Middle East remains the federal government's top priority as the war between Israel and Palestine escalates.
About 900 Israelis are dead and thousands more wounded.
At least a further 400 people were killed in Israel's retaliatory attacks and Hamas is now threatening to execute hostages if the strikes continue.
The Australian newspaper reported on Tuesday the daughter-in-law of an Australian man had been captured by Hamas militants.
Adi Kaplon, the daughter-in-law of Yonadav Kaplon, lives with her two young sons in Kibbutz Holit, 2kms from the Gaza border.
The Times of Israel reported the sons, aged four months and four, were handed to a neighbour, who hid them as their mother was taken away.
Comment was being sought from the Department of Foreign Affairs and Trade.
Defence Minister Richard Marles would not provide details of any Australian hostages, but confirmed there were no Australian casualties at this stage.
"We will be pretty reticent about talking about any individual cases," he told Seven's Sunrise program on Tuesday.
About 10,000 Australians live in Israel and many more are tourists, with authorities seeking to assess their wellbeing.
Prime Minister Anthony Albanese said there were concerns about wider conflict in the region.
"There are concerns about Australians in the Middle East ... and we continue to work through (the Department of) Foreign Affairs to provide support," he told reporters in South Australia.
He branded the taking of hostages reprehensible.
"I believe it has shocked the world for very good reasons, which is why the world has united in condemnation of it."
Foreign Minister Penny Wong urged restraint to ensure the protection of civilians.
"We call for all hostages to be released and we continue to urge the protection of all civilian lives by all parties," she told reporters in Adelaide.
But she didn't weigh in on what restraint should be exercised by Tel Aviv when it came to collective punishment after it announced it was cutting off food, water, electricity and gas to Gaza.
"It's always very difficult from over here to make judgments about what security approach other countries take," she told ABC radio.
"We've said Israel has the right to defend itself."
The foreign minister has been in contact with her Israeli and Jordan counterparts as well as with other governments "with influence in the region".
Opposition Leader Peter Dutton said the attack "was an act of terrorism and treachery".
"This is not a rudimentary incursion across a border ... these people were driven into the desert and slaughtered," he told reporters in Adelaide.
Executive Council of Australian Jewry head Alex Ryvchin said his community faced "perennial threats" during times of peace, war and heightened tensions.
"We're doing everything we can, we're consulting with police and our security advisors to ensure that our community is kept safe," he said.
Palestinian political analyst Nour Odeh said cutting aid and punishing an entire community who did not carry out the attack was "political posturing of the most sinister kind".
"Ordinary Palestinians are ... certainly not deserving of being further punished on top of the miserable reality that they live in," she told ABC radio.
The way to end the conflict was to address the root causes instead of bombing a civilian population as Palestinians "do not want to be ruled by a foreign military", the Ramallah-based analyst said.
Australia Palestine Advocacy Network president Nasser Mashni said he couldn't condone violence, but questioned why Palestinian voices were only heard when Israel was attacked but not when 250 of his people were killed this year.
"No building has been ever lit up in the Palestinian flag," he told ABC TV.
