Retired American boxing great Muhammad Ali is not happy with the comments made by Republican presidential candidate Donald Trump against Muslims, and he is upset that the business magnate is even thinking of banning Muslim entry into the United States in light of the terror attacks that occurred in different parts of the world recently.

Even though he did not specifically name Trump, his comment came three days after Trump posted on his personal Twitter account (@realdonaldtrump) that he has never met any great Muslim athletes—even though he has met with Ali several times already.

In a statement obtained by NBC News, Ali said: "We as Muslims have 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."

His statement, which was headlined "Presidential Candidates Proposing to Ban Muslim Immigration to the United States," also stressed that there is nothing Islamic about killing innocent people in Paris, San Bernardino, or anywhere else in the world.

"True Muslims know that the ruthless violence of so-called Islamic jihadists goes against the very tenets of our religion," he said. "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."

Trump earlier warned that America is facing a major threat from radical Islamic terrorism, noting how important it is for people to "get very smart, and very tough, FAST, before it is too late!"

"So many foolish people that refuse to acknowledge the tremendous danger and uncertainty of certain people coming into U.S.," he said.