Boxing legend Muhammad Ali, one of America's best-known Muslims, released a statement Wednesday criticizing "so called" Islamic extremists and those "who use Islam to advance their own personal agenda," undoubtedly a reference to Republican presidential front-runner Donald Trump, who says he wants to ban all Muslims from entering the U.S.

"I am a Muslim and there is nothing Islamic about killing innocent people in Paris, San Bernardino, or anywhere else in the world," the three-time world heavyweight champion of the world told NBC News. "True Muslims know that the ruthless violence of so called Islamic Jihadists goes against the very tenets of our religion."

While the statement never mentions Trump by name, the letter's headline, "Presidential Candidates Proposing to Ban Muslim Immigration to the United States," leaves no question that it is directed to the real estate billionaire.

Following last week's terrorist attack in San Bernardino committed by two radical Muslims, Trump said on Monday that foreign Muslims should be temporarily barred from traveling to the country. Trump also recently questioned President Obama's affirmation that Muslim Americans are some of the nation's greatest sports heroes, tweeting that he couldn't recall any American Muslim athletes, even though he's met Ali on several occasions, according to The New York Times.

Ali, 73, who converted to Sunni Islam in 1975, called on Muslims to "stand up to those who use Islam to advance their own personal agenda. They have alienated many from learning about Islam. True Muslims know or should know that it goes against our religion to try and force Islam on anybody."

He added: "Speaking as someone who has never been accused of political correctness, 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."

The headline of Ali's statement was later changed to, "Statement from Muhammad Ali Calling on all Muslims to Stand Up Against Jihadist Radical Agenda."

Robert Gunnell, a spokesman for Ali, said the headline was changed because the statement was "not a direct response to Donald Trump. This statement was Muhammad Ali's belief that Muslims must reject Jihadist extremist views," according to Reuters.