Johnson said the word he used is like the "n-word," which at one time was acceptable to use but now is not.
"Now, we don't say the n-word. We refer to that word as the n-word," he said.
"I had never heard of the m-word. The m-word. It's a word also that describes a group of people and it at one time has been commonly used as a descriptive term," he said, adding that the use of the m-word is "no longer socially acceptable."
He said proper terms are "the little people," or people with dwarfism, and said people who wanted to find out more about this condition can look at a website run by a group called the Little People of America, www.lpaonline.org.
"So I wanted to say to all of those who may have been offended by the use of the term, the m-word, I want you to know that it was out of ignorance and not spite or hatred that I used that term, and please know that I will never use that term again," he said.
"I have been awakened to the sensitivities involved. So anyone who I offended has my deepest apology."