Deputy Prime Minister Richard Marles passionately addressed a vigil for Israeli victims in Melbourne, telling his audience "Australia's heart breaks" for them and describing the Hamas assault as an act of terrorism.
More than 1100 people are dead and thousands were wounded in Saturday's strikes and the retaliatory attacks launched by Israel.
Mr Marles spoke of "evil, extreme violence and death", described many of those killed as innocents and declared "that makes this murder".
"As Israel acts to defend herself and to seek the protection and the liberation of her citizens and to act against Hamas, Australia stands by her side," he said.
Jewish Australians at a vigil for victims of the attacks in Israel at Melbourne's Caulfield Shule.
"In 2023, it is time, around the world, that there is an acknowledgement that Israel has a right to exist in peace and with security.
"And as this right is asserted, our nation stands as one with all the people of Israel."
NSW Premier Chris Minns earlier on Monday said he was "deeply concerned about the horrific attack by Hamas on Israel and those who have been kidnapped".
Prime Minister Anthony Albanese acknowledged Israel's right to defend itself but urged Australians to be restrained, as Opposition Leader Peter Dutton took a different view.
"People who try to draw a parallel or argue equivalence between Israeli activity in their retaliation for the strikes and the barbaric attacks that we've seen by Hamas - there is no comparison," he told Sky News.
NSW Green MP Jenny Leong described Mr Marles' assessment of the Hamas attacks as unprovoked as "disgraceful" and the lighting of the Opera House as "appalling".
Deputy Prime Minister Richard Marles says Australia stands by Israel.
South Australia's parliament and Adelaide Oval, Melbourne Cricket Ground, the National Gallery of Victoria and Old Treasury Building were also bathed in blue and white on Monday.
Brisbane's Story Bridge was illuminated in Israel's national colours on Sunday.
Tensions grew at the Opera House on Monday evening when flares were lit as the Palestine Action Group Sydney staged a rally to urge the federal government to cut ties with Israel.
