"I was obviously trying to make a point about the heinous acts that Assad made against his own people last week using chemical weapons and gas," said Spicer in an interview with CNN's Wolf Blitzer. "And frankly I mistakenly used an inappropriate and insensitive comment about the Holocaust and there is no comparison. For that, I apologize. It was a mistake to do that."
The remarks in question came as Spicer tried condemning Russia's alliance with Assad in the wake of the chemical attack in Syria last week that killed more than 80 people and led the U.S. to strike an air base in Syria.
"We didn't even use chemical weapons in World War II," said Spicer during the briefing.
"You had ... someone as despicable as Hitler, who didn't even sink to using chemical weapons," Spicer added.
Given an opportunity during the briefing to provide clarification, Spicer dug a deeper hole, saying of Hitler, "I think when you come to sarin gas, there was no -- he was not using the gas on his own people the same way that Assad is doing."
Six million Jews, as well as other persecuted minorities, were killed during the Holocaust -- many in gas chambers at Nazi concentration and extermination camps.
"[Hitler] brought them into the Holocaust center," said Spicer at the briefing, apparently referring to the camps.
"But I'm saying that in the way that Assad used them, where he went in towns, dropped them down to innocent -- into the middle of towns -- it was brought, so the use of it -- I appreciate the clarification," he continued, concluding, "That was not the intent."
On CNN, asked whom specifically he was apologizing to, Spicer addressed "anyone offended by the comments" and admitted he "was trying to draw a comparison for which there shouldn't have been one."
"It was insensitive and inappropriate," said Spicer, later adding, "It was a mistake. I shouldn't have done it. I won't do it again."
The press secretary, who is gaining a reputation for verbal missteps -- including remarks Monday regarding the U.S.'s position taking military action in Syria that were later walked back -- further added that he was, in fact, aware of the gas chambers used by Hitler and the Nazis in the widespread genocide, continuing to chalk his gaffe up to a "mistake."
Spicer did not comment on whether President Donald Trump had asked for him to apologize, saying only that he "did not want to be a distraction" to the action taken by Trump in Syria last week.