Australia is doing everything it can to thwart terror attacks similar to the London rampage but the sobering reality was no country could guarantee it could stop every attack, Foreign Minister Julie Bishop said.
Ms Bishop said it appeared no Australians were among the victims of the incident that left five people dead, 20 injured and forced the lockdown of British parliament.
"Most certainly in Australia we have invested heavily in ensuring our law enforcement agencies, our intelligence agencies, our authorities are in a position to thwart attacks, but I can't give any guarantees," Ms Bishop told reporters in Washington DC on Wednesday.
"No country can.
"We must continue to be vigilant and ensure our resources, our investment is able to do the best we can to keep Australia safe."
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Pedestrians and sightseers on the popular London tourist site and thoroughfare, Westminster Bridge, were mowed down by a vehicle.
It is believed the assailant in the car then approached parliament where he fatally stabbed an armed police officer.
News of the attack reached Ms Bishop in Washington DC as she met with US Secretary of State Rex Tillerson, British Foreign Secretary Boris Johnson and senior officials from 65 other nations that form a coalition aimed at defeating the Islamic State terror group.
Ms Bishop said it was too early to confirm the London attack was IS related, although it has the "hallmarks" .
All 68 nations re-committed at the summit to defeat IS, assist the Iraqi government to find political reconciliation and a political solution in Syria "because the military solution would not be the end of the matter".
As IS loses ground in Iraq and Syria there are fears foreign fighters will attempt to return to their home nations, including Australia, to launch terror attacks.
Ms Bishop said Australia was tracking individuals deemed a threat and working with partner countries in the Middle East, Europe and Asia.
Terrorists have used vehicles in France, Germany and Britain to kill pedestrians and Ms Bishop said Australian authorities are as well "prepared as we can be to thwart any such attack".
"We are certainly aware of this possibility, we have seen it elsewhere in the world and we learn lessons from every attack and Australia has certainly taken onboard the examples we have seen in other countries," she said.
Mr Tillerson said the US would set up "interim zones of stability" to help refugees who fled IS and al Qaeda in Iraq and Syria to return home.
Ms Bishop said the coalition members discussed options at the summit for the zones, but did not go into a specific plan.
"There are numerous different options about how that could be achieved, and all of those options are on the table," Ms Bishop said.
Mr Tillerson also called on other countries to contribute more to the anti-IS effort.
"The United States will do its part, but the circumstances on the ground requires more from all of you," Mr Tillerson said.
