Near noon on Monday, the benchmark S&P/ASX200 index was down 4.4 points, or 0.05 per cent, to 8,612.7.
The broader All Ordinaries had dropped 12.1 points, or 0.14 per cent, to 8,827.0.
Capital.com analyst Kyle Rodda said there was little sign that the war in the Middle East was de-escalating.
"If anything, strikes intensified over the weekend and all sides are making overtures that the war could be more protracted."
The Reserve Bank of Australia, meanwhile, is expected to become the only central bank amongst the eight global banks making monetary policy decisions this week to raise rates.
All four of Australia's big banks expect the Reserve Bank to hike the cash rate to 3.85 per cent on Tuesday.
The US Federal Reserve and the central banks of Japan, China, England, the European Union, Switzerland and Sweden will all announce their decisions on interest rates over Wednesday and Thursday, local time.
At midday, four of the ASX's 11 sectors were lower, and seven were higher.
The heavyweight materials sector was the biggest mover, dropping 1.8 per cent.
Goldminers were in the red as the yellow metal fell to a three and a half week low of just above $5,000 an ounce.
Northern Star had lost 5.0 per cent, Evolution had slipped 2.7 per cent and Newmont had subtracted 3.9 per cent.
Elsewhere in the sector, Fortescue had dropped 2.9 per cent and Rio Tinto had diminished 1.6 per cent, while BHP's losses were less pronounced at 0.2 per cent.
Lynas climbed 1.3 per cent after the rare earth miner signed an offtake agreement with the US Department of War, while Orica dipped 1.6 per cent after the explosives maker settled a US lawsuit over a contract dispute.
Orica will pay $US$169.5 million to former supplier CF Industries, with neither party admitting wrongdoing.
The big four banks were all higher, with CBA up 0.7 per cent, Westpac adding 0.4 per cent and ANZ and NAB both climbing 0.2 per cent.
In the energy sector, Woodside had gained 2.5 per cent and Santos had climbed 1.9 per cent as Brent crude changed hands at $US102.90 a barrel.
Whitehaven Coal slid 4.2 per cent and uranium developer Deep Yellow lost 8.8 per cent.
In the consumer discretionary sector, Guzman y Gomez gained 3.6 per cent as the Mexican-themed restaurant chain said that co-CEO Hilton Brett would reduce his workload in preparation for a kidney transplant later in the year.
The Australian dollar was changing hands for 69.98 US cents, from 70.63 US cents at 5pm on Friday.
