WATCH: Former commanding general of U.S. Army Europe destroys Trump's 'jackassery'
U.S. Army Europe photo of Lt. Gen. Mark Hertling by George P. Harris.

Retired 3-star General Mark Hertling criticized President Donald Trump's "unprofessional" comments against retired Navy Admiral William H. McRaven during a Sunday appearance on CNN.

Trump dismissed McRaven as a “Hillary Clinton fan” while complaining that the Navy SEALs did not find Osama bin Laden sooner.

"What I would say in terms of my reaction is we can never become immune to this kind of narrative, to this kind of jackassery," Hertling declared.

Hertling served as the commanding general of U.S. Army Europe and the Seventh Army and is now a CNN military analyst.

Hertling noted McRaven is a good friend.

"We both have served during the same period of time and under multiple presidents from both parties. We serve in the military the Constitution of the United States -- we don't serve an individual," he explained. "That's what makes our military different from all the other militaries in the world."

"This comment from the president was disrespectful, demoralizing, it was shallow and it was unprofessional," he concluded.