And it would also buy unmanned aircraft to detect asylum seekers arriving by boat.
Addressing Sydney's Lowy Institute on Friday, Mr Abbott said involvement in both the Iraq and Afghanistan wars was right.
Stronger US ties
It has deepened Australia's ties with the United States and Britain as well as reinforcing its significance to the world, he said.
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But while stopping short of committing precise numbers of troops to the region, Mr Abbott said Australia could and should do more, including taking a lead role in some provinces.
He was speaking during a wide-ranging, 38-minute speech outlining the coalition's defence and national security policies.
"Putting more troops at risk is not a decision that any Australian government should lightly make but the near certainty of higher casualties has to be weighed against the consequences of failing to shoulder extra responsibilities," Mr Abbott told an audience of politicians and business chiefs.
"How fair is it to leave Australia's security so much in the hands of other countries' soldiers? Or expect America and Britain to do nearly all the free world's heavy lifting?
"If satisfied that the role made strategic sense and was compatible with our other military commitments, the coalition government would be prepared to consider doing more.
"Doing more would be a sign Australia was serious about its overseas responsibilities."
Opposition leader backs both wars
The opposition leader said he fully backed involvement in the two wars, saying terrorism and nuclear proliferation were ongoing threats to the West and other nations.
The coalition would aim to increase defence spending by three per cent a year until 2018, as was the case under the Howard government, Mr Abbott said.
It would also back the purchase of new submarines to replace the current fleet, he added.
A commitment was also made to buy three unmanned Global Hawk Surveillance aircraft to aid detection of asylum seekers arriving by boat.
"These aircraft would help to protect the vast oil and gas projects now progressing on the North West Shelf," Mr Abbott said.
"Real-time surveillance and their vast area of coverage should allow much earlier detection and interception of illegal boat arrivals.
"Improved intelligence would also make it easier to track and help boats in danger of sinking."
A detailed defence policy containing fully costed plans to fund capital acquisitions would be released nearer to the federal election, Mr Abbott said.
