Statement urges US and allies to consider the innocent
In a joint statement, 14 organisations warned of a "descent into a spiral of violence".
The groups - including Christian Aid and Amnesty International UK - urged the US and its allies to apply "measured thought and statesmanship".
They also called on them to consider the impact of military action on "the poor, the innocent and the voiceless".
"Thousands of innocent people have died in the United States," the charities said.
"We must now make sure that even more innocent lives are not lost."
They added: "It is imperative that hatred does not become the order of the day, that fear does not become an excuse for the violation of rights and that we all remember our common humanity.
"It is dangerously easy to demonise particular groups and peoples.
"Already there have been threats and attacks against Muslim communities and individuals, in this country and beyond."
The Muslim Council of Britain has also warned that "blameless people" should not pay a price for the attacks.
Christian Aid spokesman Jon Barton told BBC News Online: "We are very all concerned about the lasting consequences of a situation that could create more bitterness, resentment and terrorism."
"Greatness lies in upholding justice, even under such dire circumstances," the MCB said.
"This is an opportunity for the world community to demonstrate its core values and principles remain triumphant, in direct contrast to the barbarity of those that committed this atrocity."
The groups making the joint statement are: Christian Aid, ActionAid, Amnesty International UK, Catholic Agency For Overseas Development, Catholic Institute of International Relations, Oxfam GB, Refugee Council, Saferworld, Save the Children UK, World Development Movement, Voluntary Service Overseas, Children's Aid Direct, Concern and Tearfund.