Kofi Annan, opening the second meeting of the UN-organised Alliance of Civilisations (AOC) in Doha, Qatar, urged members to build a compelling dialogue to counter the hatred and mistrust seen in the row over the cartoons.
"The passions aroused by the publication of insulting cartoons of the Prophet Muhammad, and the reaction to it, show only too clearly that such threats are real and that the need for a committed effort by the international community is acute," he said.
Free speech, Annan said, was about listening as well as talking.
He said world leaders needed to communicate a message of unity, making clear that diversity was a precious asset and should not be polarised into threats.
Annan said the recent furore over the cartoons illustrated how different perceptions and understandings could inflame cracks in society, igniting into violence when values collided.
Speaking after Annan's address, the Qatari prime minister said he was looking to the group to address issues of extremism and terrorism and ways to understand how they start from a wellspring of mistrust and hatred of other peoples and cultures.
"The passions aroused show only too clearly that such threats are real and that the need for a committed effort by the international community is acute"
UN secretary general
"Current circumstances require us to examine in depth the West, East, North and South and different peoples and cultures so that we may better understand each other," Sheikh Abdullah bin Khalifa Al Thani said.
"Regardless of our backgrounds, we need much effort to grasp the values we hold in common and agree on the red lines that should not be passed when we differ."
Other delegates attending the start of the three-day conference were the Amir of Qatar, Sheikh Hamad Bin Khalifa Al Thani, as well as former Iranian President Mohammed Khatami and Amr Moussa, the head of the Arab league.
The AOC grouping first met in Majorca last year at the behest of Turkey and Spain.
It was then taken up by the United Nations with the aim of bringing together prominent individuals from around the world to construct a dialogue and bridge differences between civilisations, such as between Islam and the West.
The AOC has 21 members selected by the UN to help encourage cross-cultural dialogue. They are set to publish the results of their work by November 2006.
On the eve of the conference on Saturday, Annan issued a joint communiqué along with European and Islamic representatives condemning the publication of the cartoons, regarded as blasphemous by Muslims.
The cartoons have sparked
protests across the Muslim world
He said he would take up the case at the UN General Assembly and the Security Council, seeking a joint international decision on the issue.
Asked what action the UN would take on blasphemy in the context of the cartoon controversy, Annan said: "We understand and respect Muslim sentiments on the issue.
"I will submit this statement before the UN General Assembly and the UN Security Council. I can not commit anything since it is the member countries to decide on the issue."
Ekmeleddin Ihsanoglu, the Secretary-General of the Organisation of Islamic Countries and Miguel Angel Moratinos, the Spanish Foreign Minister, also signatories to the statement, said they were pressing European Union leaders to come up with a decision on the issue.
The EU has yet to make any direct statement on the cartoons, although some senior officials have defended the right to publish them in the context of freedom of expression.