Brussels: Iranian Foreign Minister Mohammad Javad Zarif told European Union lawmakers on Tuesday militants were also a European problem.
European parliamentarians quizzed Zarif about alleged human rights violations in Iran, Iranian defence spending and nuclear activity and Tehran's stance on Middle East conflicts that have killed hundreds of thousands of people and driven millions from their homes, spurring a large influx of refugees into Europe.
Radicalised European citizens, often with immigrant backgrounds, have gone to Syria and Iraq to fight for IS militants, who claimed responsibility for the shooting and bombing rampage in Paris that killed 130 people in November.
"We all need to understand why some who behead innocent individuals in our part of the world speak European languages with perfect accents. Why is it that this is happening?" Zarif told the European Parliament session.
"You feel the consequences of the growth of extremism in our region in terms of refugees that come to Europe, in terms of the spread of unfortunate terrorist incidents in various European cities. Extremism cannot be contained in one country or one region, it's a global menace, requiring a global response."
In Syria, an offensive by government forces backed by Russian air strikes and militias has regained significant ground from rebels in the north near Turkey's frontier, dimming prospects that a truce deal hatched by world powers in Munich last week will take hold soon.
Zarif said Tehran had no "boots on the ground" in Syria but only "military advisers" on the invitation of Syrian President Bashar Al Assad.
"We will move out military advisers when the local government deems it necessary for us to remove them," Zarif said. "Why is Iran there? Because Iran believes that the alternative right now - either in Iraq or in Syria - is not a democratic government but IS."
Syria's war created a breeding ground for the ultra-radical IS, whose insurgents now control large swathes of territory in Syria and neighbouring Iraq.
Russia has come under criticism for not ceasing air strikes in Syria since the Munich agreement and has faced accusations that it was using lengthy and complex Syria diplomacy only to buy time to turn the tide of the war on the ground.
Zarif challenged that, saying: "Who is going to impose the military solution in Syria? Nobody. Russia can't impose a military solution either... We need a political solution."
"Are we talking about democracies in our region criticising Bashar Al Assad?" Zarif said. "This is not about democracy, this is not about the rights of the Syrian people. This is all about a convoluted, perverted concept of regional equilibrium, which they believe has been disturbed and they want a redress."