"Our strategy must work in tandem with Arab states, always in support of local people, in line with our legal obligations and as part of a plan that involves our aid, our diplomacy and, yes, our military," Efe quoted Cameron as saying at a meeting of the UN Security Council in New York. "We need to act and we need to act now," he said.
It is expected that, in his Thursday speech before the UN, Cameron will provide details concerning British aid for the US-led international effort against the IS.
Cameron: We need to act and we need to act now
Cameron on Wednesday convened an extraordinary session of Parliament to debate Britain's response to an Iraqi government call for London to join the offensive against the jihadi group, an effort that has included hundreds of mainly-US airstrikes on IS positions in Iraq and Syria.
Intervention in Iraq is a very sensitive subject in Britain after the controversy over Britain's participation in the 2003 Iraq war, a campaign launched by then-Prime Minister Tony Blair.
The British government is particularly concerned about IS violence after the jihadis beheaded British hostage David Haines and US journalists James Foley and Steven Sotloff. The Islamist group is now threatening to kill another British hostage, Alan Henning.