2016 Republican presidential frontrunner Donald Trump defended himself Thursday after being criticized for a speech in which he appeared to mock a reporter with a disability – although the business mogul says his mimicking had nothing to do with the reporter’s condition.

Jay Ruderman of the Ruderman Family Foundation in Boston said the Republican presidential contender should apologize to Serge Kovaleski of The New York Times and the public.

Trump was challenging recollections by Kovaleski and many others about the aftermath of the 9/11 terror attacks. Trump has been criticized for claiming that thousands of Muslims in New Jersey were seen celebrating the attacks on the World Trade Center in New York.

Trump and his supporters have cited articles written at the time that appeared to back Trump’s claims, at least to an extent.

In 2001, Kovaleski, then with The Washington Post, and another Post journalist wrote a week after the 9/11 attacks about authorities in New Jersey detaining and questioning "a number of people who were allegedly seen celebrating the attacks."

Trump has pointed to the Post story as backing up his claim and took issue with Kovaleski's recent statement that he did not remember anyone alleging that large numbers of Muslims were celebrating.

Kovaleski has a congenital condition that affects joint movement. In a speech Tuesday in South Carolina, Trump said: "poor guy, you oughta see this guy," and gestured in a jerky fashion as he imitated the reporter.

“‘Uh, I don't know what I said, uh, I don't remember.’ He's going like, I don't remember,’" Trump said, while shaking.

After Trump’s latest comments, The New York Times expressed outrage afterward that Trump would "ridicule the appearance of one of our reporters."

Ruderman said Trump would benefit from a "series of sensitivity training sessions" and offered to provide them.

"It is unacceptable for a child to mock another child's disability on the playground, never mind a presidential candidate mocking someone's disability as part of a national political discourse," he said.

However, in a statement released to Twitter, Trump denied that he had mocked Kovaleski’s disability.

“I have no idea who this reporter, Serge Kovalski [sic] is, what he looks like is his level of intelligence,” Trump said.

“In my speech before over 10,000 people in Myrtle Beach, SC, I merely mimicked what I thought would be a flustered reporter trying to get out of a statement he made long ago,” Trump said.

Trump went on to cite his respect for disabled people and how he has spent millions of dollars making his buildings handicapped accessible. He then went on to criticize the New York Times for attacking him on the issue.

“”This is just another example of the dishonest New York Times trying to make a story out of nothing. They should focus on the survival of their newspaper and not on dishonest and very bad reporting about me,” Trump said.

The Associated Press contributed to this report.