God commands justice and doing good and giving to relatives. And He forbids indecency and doing wrong and tyranny. He warns you so that hopefully you will pay heed. (Qur'an, 16:90)
As Muslims, we strongly condemn all the terrorist attacks around the world, including those on two major cities of the United States of America on September 11, 2001, which caused the death and injury of thousands of innocent people.
the destruction of the twin towers
9/11 attacks propelled the important issue of the true source of terrorism to the top of the world agenda. Thus, it has been announced to the entire world that Islam is a religion of peace and love that summons individuals to compassion and justice. Many world leaders, leading media organizations, television and radio stations said that in true Islam the violence is forbidden, and peace between people and between nations is encouraged. The Western circles that have come to a full grasp of the religion of Islam and are well-informed about Islam as commanded by God in the Qur'an noted clearly that the words "Islam" and "terror" cannot stand side by side, and that no divine religion permits violence.
http://www.harunyahya.com/en/Books/735/islam-denounces-terrorism