Protesters will march in solidarity with Palestinians in Sydney, as Australia's Jewish community mourns the victims of renewed conflict in Israel.
More than 700 Israelis are dead and thousands more wounded after Palestinian Islamist militant group Hamas launched attacks on Saturday, sparking condemnation from Australian leaders.
Videos of the offensive show the abduction of children and elderly women by militants, as well as the naked body of a woman being paraded through the streets before being spat on.
Israel has retaliated, striking housing blocks, a mosque and the homes of Hamas officials in Gaza.
More than 400 people have been killed, including 20 children.
A pro-Palestine rally will be held at the Sydney Opera House on Monday evening, as the landmark is lit up in the blue and white colours of the Israeli flag.
A vigil for Israeli victims will be held in Melbourne.
In Sydney's southwest, a Muslim preacher told a crowd gathered in Lakemba on Sunday night, the attacks were an act of resistance.
"I'm smiling and I'm happy," he said.
"I'm elated, it's a day of courage, it's a day of pride, it's a day of victory. This is the day we've been waiting for."
Police are investigating after footage emerged showing people shooting red and green fireworks out of a ute along a main road in neighbouring suburb Greenacre.
Passengers in the car waved a Palestinian flag in celebration as the car horn was blown.
Executive Council of Australian Jewry spokesman Alex Ryvchin condemned the rally as "sickening".
"It's truly devastating and sickening to see such inhumanity in our midst," he told reporters in Sydney.
"I place the blame at their leaders, at the clerics that incite them, that tell them that this is okay ... they need to be held to account for this."
Australian Palestine Advocacy Network president Nasser Mashni has said the action was in response to an escalation of attacks from Israel.
"Israel hasn't been defending itself, it's been waging war on Palestinians each and every day for decades," Mr Mashni said in a statement.
The vigil paying tribute to the killed Israelis will be held at a synagogue in Melbourne on Monday evening.
In Canberra, Parliament House will also light up in solidarity with Israel, as will other landmarks in Melbourne and Adelaide.
Australia is urging people not to travel to Gaza or areas near its border and is advising people in Israel and occupied Palestinian territories to exercise a high degree of caution.
Hamas' operation came a day after the 50th anniversary of the Yom Kippur War, a surprise attack by Egypt and Syria in 1973.
Prime Minister Anthony Albanese said the planned rally supporting the attack should not go ahead.
"Out of respect for the loss of life ... there's no doubt there's been and continues to be Palestinian suffering," he told 2GB radio.
"But the actions of Hamas in this are completely indefensible."
Foreign Minister Penny Wong labelled the attacks "abhorrent".
"We unequivocally condemn the indiscriminate targeting of civilians and the taking of hostages," Senator Wong said at Melbourne Airport on Monday.
Opposition Leader Peter Dutton said the coalition "utterly condemns the unprovoked and abhorrent attack by militant Hamas on Israel".
