Air raid sirens blared from speakers as young and old protesters, dressed head to toe in red, gathered at Princes Park to show their support for Israel during the escalating conflict in the Middle East.

Federal Labor MP Mark Dreyfus told the crowd that Israel was defending itself as any country would.

"Imagine if any part of Australia was under attack in the way Israel has been under constant attack from Gaza now for years and years and years and years. Of course Australia would respond. So too, must Israel respond."

The peaceful rally comes as Israeli airstrikes killed at least 14 Palestinians in Gaza overnight in retaliation to ongoing rocket attacks by Hamas.

Mr Dreyfus read a statement released by Prime Minister Julia Gillard on Friday, saying he was pleased to be part of a government who brought "such clarity to the need to support Israel".

Zionist Federation of Australia president Philip Chester said Israel had been subjected to more than 12,000 rockets in 12 years.

"Such attacks on Israel's population are utterly unacceptable."

Victorian Liberal Senator Scott Ryan and state Liberal MP David Southwick also addressed the crowd, defending Israel's decision to retaliate against ongoing rocket attacks by Hamas.

"Every citizen has a right to expect that they can live in peace and every government has a duty to defend that," Mr Ryan said.

Pro-Palestinian demonstrators held a "snap protest" in Melbourne's CBD on Saturday, and warned that they would hold a larger protest next Friday.