Australia has joined fellow G20 members in pledging a tougher fight against violent extremism and boosting the global economy.
The annual summit, being held in the Turkish resort city of Antalya, was due to wrap up on Monday with statements on terrorism and economic growth.
"This G20, I believe, will be known for its commitment to defending our collective national security, standing up against terrorism, doing everything it can to ensure the claims of these terrorists are refuted at every level - and at the same time promoting economic growth and jobs," Mr Turnbull told reporters.
He said G20 leaders, who met for a working dinner to discuss terrorism and Syria's future, were "utterly united" to defeat terrorism.
G20 leaders with majority Muslim populations added their voice to condemnation of Islamic State and similar groups.
"(They said) they are an abomination to religion and they reject them utterly," Mr Turnbull cited the Muslim leaders as saying.
He said economic issues had held equal importance at the summit, although "headwinds" were making it hard for the countries to meet a target set in Brisbane of more than two per cent growth above the current trajectory to 2018.
"The commitment remains," he said of the target.
Foreign Minister Julie Bishop told reporters in Manila, where she is attending APEC meetings, Australia had received no request to increase its mission in Syria - which currently involves air strikes.
Ms Bishop declined to pre-empt what US President Barack Obama might say to Mr Turnbull at a bilateral meeting in Manila on Tuesday, when the Iraq and Syria conflicts will be discussed.
Mr Obama and Russian leader Vladimir Putin met for 35 minutes on the G20 sidelines on Sunday, agreeing on the first steps towards peace in Syria - which has been wracked by civil war and violence instigated by Islamic State.
The two leaders agreed on the need for United Nations talks, a ceasefire and a transition government in Syria, echoing a plan for Syria already forged by diplomats at talks in Vienna the previous day.
The final G20 communique, which was due to be released at 3pm (midnight AEDT), was expected to cover financial regulation, international tax, anti-corruption and reform of the International Monetary Fund.
As well there will be statements on refugees, climate change, energy and free trade.
Mr Turnbull met with Chinese President Xi Jinping on the sidelines of the G20 summit to discuss the rollout of the free trade agreement which the Australian parliament has passed.
