United States defence secretary Jim Mattis noted in a separate briefing that "the intent was to stop the cycle of violence into an area that even in World War II chemical weapons were not used on battlefields".
Watch video of Melissa McCarthy's Sean Spicer impression when it becomes available.
"I think when you come to sarin gas, there was no, he (Hitler) was not using the gas on his own people the same way that Assad is doing", Spicer said.
But Matt Brooks, executive director of the Republican Jewish Coalition, said that while "using the issue of the Holocaust or Hitler is problematic on many levels", he believed Spicer had "genuinely and sincerely apologized". "I got into a topic that I shouldn't have and I screwed up", Spicer said.
Ten minutes later, Mr Trump tweeted: "For eight years Russian Federation "ran over" President Obama, got stronger and stronger, picked-off Crimea and added missiles".
After making the initial comment, Spicer was asked about it again during the briefing but offered a garbled defense in which he tried to differentiate between Hitler's actions and the gas attack on Syrian civilians last week. "But I'm saying in the way that Assad used them, where he went into towns, dropped them down, to innocent - into the middle of towns".
News broke that the White House Press Secretary dressed as the Easter Bunny during the Bush administration, giving fodder for comedians like Jimmy Kimmel.
President Donald Trump's press secretary Sean Spicer has apologised for his "insensitive" remarks in which he said Adolf Hitler, who gassed millions of Jews during the Holocaust, did not use chemical weapons, drawing instant rubuke from leaders and the Jewish community. Although President Trump did record his first interview since entering the White House with the channel on Tuesday so Mr Spicer may have been more likely to be paying attention to the network.
In January, the spokesman was ridiculed after claiming Mr Trump had "the largest audience ever" for his inauguration - despite images showing large, empty spaces around the Washington Monument. "There was clearly. I understand your point, thank you".