The Taoiseach and the Tanaiste as well as cabinet ministers joined in a special commemoration service at the US Embassy.
Bertie Ahern told the gathering in Ballsbridge, Dublin that we must remain relentless in the pursuit of peace and security wherever it is absent or under threat.
He said the causes of conflict must be addressed.
Foreign Affairs Minister, Brian Cowen, who is in New York, stressed the solidarity shown by Irish people towards Americans.
"In representing the people of Ireland at a special ceremony of commemoration here I think I will carry with me a deep sense of solidarity with the relatives of the victims and their friends and families."