Iraqi government spokesman Ali al-Moussawi expressed hope that the international attention could produce a consensus on what to do next.
"The world must unite to eradicate this organization and those alike. It is supported by countries, organizations and individuals and it cannot be eliminated unless we fight this extremism in all possible ways," he said.
One thorny question is how to cut off funding for the Islamic State fighters. Some accuse Qatar of being among their financial backers, which the government denies. Qatar's Foreign Ministry on Thursday condemned Foley's killing, saying it was "a heinous crime that goes against all Islamic and humanitarian principles, as well as international laws and conventions."
Interpol didn't give any specific recommendations but is particularly concerned that a man who appears in a video of journalist James Foley's death may be British.
"(This highlights) the need for a multilateral response against the terror threat posed by radicalized transnational fighters travelling to conflict zones in the Middle East," said Interpol Secretary-General Ronald Noble.
More than a thousand radicals from Europe have joined militant fighters in Syria and Iraq, and Interpol has long warned of the threat such fighters pose. European governments worry those radicals could stage attacks when they get home and have introduced new anti-terrorism measures to try to catch them or stop them from leaving in the first place.
French President Francois Hollande urged other countries to wake up to the threat of the group.
"It's not simply a terrorist group like those, alas, we have already known — dispersed, scattered, with several chiefs. This is a terrorist enterprise that has decided to enslave, annihilate, destroy," he said Thursday.
France, which has seen an unusually large number of its citizens travel to fight with the Islamic State group, was the first European country to send arms to Iraq and has pushed its European counterparts to do more.
Within Europe, any concerted action in Iraq is complicated by uncomfortable memories of the U.S.-led invasion of Iraq in 2003.
There were no immediate signs of a shift in British policy in the wake of Foley's slaying. Britain has already said its mission in Iraq has moved beyond the humanitarian phase and includes Royal Air Force reconnaissance patrols. Britain has also said it is willing to arm Kurdish troops fighting the Sunni insurgents.
Prime Minister David Cameron condemned the "brutal and barbaric" killing of Foley but said Britain would not take any "knee-jerk" action.
"I have been very clear that this country is not going to get involved in another Iraq war. We are not putting combat troops, combat boots on the ground," he said.
Germany announced it is sending arms to Kurds fighting the extremists and said Foley's death played a role in the decision, which it had been considering for weeks. Government spokesman Steffen Seibert told reporters in Berlin the video posted online of Foley "shows the barbaric and completely merciless murder of a human being."
Jill Lawless in London, Juergen Baetz in Brussels, Vivian Salama in Baghdad, Adam Schreck in Dubai, Frank Jordans in Berlin, Ciaran Giles in Madrid, Elena Becatoros in Athens contributed to this report.