In the wake of the July terrorist bombing attacks on London, the Fiqh Council of North America, an 18-member group of Muslim legal scholars, issued the edict as an interpretation of Islamic law for the nation's Muslim community, which some estimate to number as many as 6 million.
"All acts of terrorism targeting civilians are haram (forbidden) in Islam," the fatwa said.
Further, it said, "It is haram for a Muslim to cooperate with any individual or group that is involved in any act of terrorism or violence."
The edict went on to say that "it is the civic and religious duty of Muslims to cooperate with law enforcement authorities to protect the lives of all civilians."
The fatwa was read at a Washington press conference, and has been endorsed by 120 Muslim organizations across America, including the Council on American-Islamic Relations (CAIR).
"United, we can confront the terrorists and frustrate their goal of sparking an apocalyptic war between faiths and civilizations," said CAIR's executive director, Nihad Awad.
Since the attacks on London, two groups of British scholars have issued fatwas condemning the attacks and terrorist tactics. While one fatwa categorically disallowed all suicide bombings, the other allowed for suicide attacks in some instances, such as when a country is occupied by a foreign force.
The American fatwa did not specifically mention suicide bombings in the context of war, but it did say that those who attack innocent civilians "are criminals, not `martyrs."'