"The position of the Holy See concerning the military action of 2002-2003 is well known. Everyone can see that it did not lead to a safer world either inside or outside Iraq," Vatican Foreign Minister Monsignor Giovanni Lajolo said in his address.
It was the first speech to the assembly by a representative of the Holy See, which holds observer status at the UN. The Vatican was only given the right to speak at the annual assembly in July.
According to a text of the speech made public by the Vatican on Thursday, Lajolo condemned terrorism as "an aberrant phenomenon, utterly unworthy of man".
"It seems obvious that terrorism can only be effectively challenged through a concerted multinational approach ... and not through the politics of unilateralism," said Lajolo.
The official, appointed the Vatican's top foreign official by Pope John Paul II last year, said that while the fight against terrorism meant "neutralising its active breeding grounds", more important was "long-term action, directed with foresight and patience, at its roots".
He said terrorism had already assumed global dimensions, and "today no state can presume to be safe from it".
"It seems obvious that terrorism can only be effectively challenged through a concerted multinational approach ... and not through the politics of unilateralism"
Monsignor Giovanni Lajolo,
Vatican foreign minister
Turning to the Middle East, he said Israeli and Palestinian leaders "have the grave duty to demonstrate their desire for peace" and urged them to follow the road map for peace "with determination and courage".
He reminded delegates that there could be no justice in the Middle East without mutual forgiveness. "This clearly requires greater moral courage than the use of arms," he said.
As for the future of the body, which failed to prevent the US and Britain from going to war in Iraq, Lajola said the UN should be given "special prerogatives to facilitate action to prevent conflicts at times of international crisis".