Israel says it has carried out its largest wave of strikes against Lebanon since the start of the war, leaving at least 250 people dead, according to local authorities.
In a joint statement with the United Kingdom, Indonesia, Jordan, Brazil, Colombia, and Sierra Leone, Foreign Minister Penny Wong called for an urgent end to the fighting in Lebanon.
"The ceasefire is fragile, but the world needs it to hold," she told ABC TV on Thursday.
"There is a risk that continued conflict in Lebanon will risk the ceasefire itself across the region.
"We want to see the Strait of Hormuz open so that Australians and the world can see lower prices for fuel."
She said the deadly attacks overnight were "deeply concerning".
The Israeli strikes on Lebanon follow Iran's agreement on Wednesday to a two-week ceasefire with the US and Israel, which would reopen the Strait of Hormuz for oil trade.
Iran says Lebanon is included in that now-shaky deal and has reportedly closed the crucial shipping route again in response to the Israeli attacks.
The US and Israel say Lebanon was never part of the peace deal.
Israeli President Benjamin Netanyahu has also declared his country is ready to return to fighting in Iran at any moment, because it still has objectives to achieve.
"The finger is on the trigger," he said in remarks translated from Hebrew.
Opposition defence spokesman James Paterson said he was sceptical of Iran's claims that Lebanon was not included in the ceasefire but expressed concern about the scale of Israel's attacks.
"Certainly we're concerned about civilian deaths in conflicts like these," he told ABC Radio on Thursday.
"Clearly what we have is a dispute between the parties to this conflict about the terms of the ceasefire."
