"They are entirely different realities," de Blasio, a 2020 Democratic presidential hopeful, told MSNBC's "Meet The Press Daily."
"And so she was wrong, and you would be critical of her, you would tell her not to use that language?" asked host Chuck Todd.
"I respect her greatly and I feel very close to her in terms of philosophy, but of course she was wrong," de Blasio said of Ocasio-Cortez. "You cannot compare -- what the Nazis did in concentration camps, unfortunately, is without any historical -- I mean, it's a horrible moment in history. There is no way to compare."
De Blasio also criticized statements by former Vice President Joe Biden in which Biden recalled how he had worked with segregationists to "get things done" while a member of the U.S. Senate.
"We can't have a Democrat talking about that broken past as if there was virtue in it," de Blasio said.
Ocasio-Cortez has refused to apologize for her comparison and blasted congressional Republicans for what she saw as a reluctance to address migrant conditions at the border. "I will never apologize for calling these camps what they are," she tweeted earlier Wednesday. She has also claimed that she was not comparing the detention centers to Nazi death camps, but rather to earlier camps, which she said focused on "mass detention of civilians without trial."