Tony Blair has launched an attack on "elements of the government of Iran" on the final day of his Middle Eastern tour.
And to combat more radical elements moderate Muslim states need to come together in an "alliance of moderation" the prime minister argued in a speech to business leaders in Dubai.
"There are elements of the government of Iran openly supporting terrorism in Iraq to stop a fledgling democratic process, trying to turn out a democratically elected government in Lebanon, flaunting the international community's desire for peace in Palestine," he said today.
"At the same time [this element] is denying the Holocaust and trying to acquire nuclear weapons capability. And yet a huge part of world opinion is frankly almost indifferent.
"It would be bizarre if it weren't so deadly serious."
Iran is yet to recognise Israel and president Mahmoud Ahmadinejad called for the country to be "wiped off the map" last year.
Additionally, international pressure has been mounting on the Middle Eastern state over its decision to re-start its nuclear programme - although Iran claims all uranium enrichment activities are aimed at nuclear power and not weapons.
Mr Blair was, however, keen to point out that his quarrel was with the government of Iran and not its people, religion or traditions.
"We must recognise the strategic threat the government of Iran poses - not the people, possibly not all of its ruling elements, but those presently in charge of its policy," the prime minister said.
"They seek to pin us back in Lebanon, in Iraq and in Palestine. Our response should be to expose what they are doing, build the alliances to prevent it and pin them back across the whole of the region."
And the threat was not only against the west or other faiths, Mr Blair stressed.
"We must mobilise our alliance of moderation in this region and outside it and defeat the extremists," he said.
"These forces of extremism based on a warped and wrong-headed interpretation of Islam aren't fighting a conventional war, but they are fighting one against us.
"And 'us' is not just the West, still less simply America and its allies. 'Us' is all those who believe in tolerance, respect for others and liberty.
"We must mobilise our alliance of moderation in this region and outside it to defeat the extremists."
Mr Blair's tour of the Middle East has lasted seven days, and included visits to Turkey, Egypt, Iraq, the West Bank and Israel.