"The ISIL activity is the direct consequence of the US occupation of Iraq, they should have not invaded Iraq. And when [militants] saw what is happening in Syria they went there, too," Brahimi said in an interview.
He added that the airstrikes, currently carried out by a US-led coalition against the ISIL positions in Syria and Iraq, did not prevent the spread of the jihadist cause in the region.
"Terrorism must be countered. An attempt was made to combat terrorism with aviation. But airstrikes do not solve the problem. These methods cannot resolve the political situation created by the ISIL," Brahimi said.
Brahimi also hailed Russia's contribution to reconciliation attempts looking to bring an end to the ongoing civil war in Syria after Moscow hosted two rounds of intra-Syrian talks this year.
"There are no differences between us and Russia. We recognize that Russia has an important role, which we fully support… The efforts taken earlier by Russia in a bid to bring together some of the sides is the right direction," Brahimi said.
The IS militant group controls large parts of Iraq and Syria and is notorious for publishing numerous videos showing many human rights atrocities including beheadings of foreign hostages.