"The timing and the manner of China's announcement are unhelpful in light of current regional tensions, and will not contribute to regional stability," Foreign Minister Julie Bishop said in a statement.
"Australia has made clear its opposition to any coercive or unilateral actions to change the status quo in the East China Sea."
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Bishop said the Department of Foreign Affairs and Trade called in China's ambassador on Monday "to convey the Australian Government's concerns and to seek an explanation of China's intentions".
China's declaration of an air defence zone over much of the East China Sea has sharply escalated tensions in the region.
China and Japan each summoned the other's ambassador after Beijing said Saturday it had established an Air Defence Identification Zone -- which would require aircraft to obey its orders -- over an area that includes islands administered by Japan.
The US and Japan have vowed not to recognise it.
China is Australia's biggest trading partner and newly elected Prime Minister Tony Abbott has said he hopes to conclude a free trade agreement with Beijing within a year as he pushes for deeper ties with the Asian giant.
But Washington remains Canberra's key ally, and last month Foreign Minister Bishop said the new government in Canberra intended to keep Japan as its "best friend" in Asia, as it works on relations with China.