The boxing great dedicated the last few years of his life to promoting Islam and he became a "voice for Muslims", according to Usama Shami, president of the Islamic Community Centre of Phoenix.
Prayers were dedicated to the three-time world heavyweight champion on Friday after the local Muslim community was left "shocked" by Ali's death, he said.
"He was a voice for Muslims that was more accepted by many Americans than the voices of other Muslims," Mr Shami told the Press Association.
"We have lost someone who is a champion of Islam, who is respected and who spoke against violence.
"For the last years of his life, he was helping to promote the idea of Islam.
"He spoke about Isis to distinguish between Islam and Isis and say those people do not represent Islam."
Ali issued a statement in December criticising Islamic extremists and Donald Trump's proposal to ban Muslims from entering America.
Without naming the US Republican presidential hopeful, Ali said Muslims "have to stand up to those who use Islam to advance their own personal agenda".
"I am a Muslim and there is nothing Islamic about killing innocent people in Paris, San Bernardino, or anywhere else in the world," he wrote.
"True Muslims know that the ruthless violence of so called Islamic Jihadists goes against the very tenets of our religion.
" I believe that our political leaders should use their position to bring understanding about the religion of Islam and clarify that these misguided murderers have perverted people's views on what Islam really is."
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