"It is an extremely difficult affair, but France does not want war," the president said on Thursday, in a live interview on French television.
Earlier Bernard Kouchner, France's foreign minister, had said that the world should "prepare for the worst" over Iran, adding that "the worst is war".
He has since tried to play down his comments.
In his television interview Sarkozy said: "Iran is trying to get a nuclear bomb. I have said this is unacceptable and I tell the French people that it is unacceptable."
But he said that he hoped a mix of negotiations and sanctions would persuade Iran to drop its nuclear ambitions.
France, which has taken a tougher stance against Tehran since Sarkozy came to power in May, is looking to impose fresh economic sanctions and convince other EU countries to force their companies to boycott Iran.
The meeting on Friday between France, Britain, Germany, the US, Russia and China will discuss a possible third round of UN sanctions over Iran's nuclear programme that France, the US and others say could be used to make nuclear weapons.
Iran denies that it is seeking nuclear weapons and says it only wants nuclear technology in order to generate electricity.