Asked by CNN host Chris Cuomo whether he respects Trump, the South Bend, Ind. mayor said he respects the office, but Trump has "done nothing to command my respect."
Cuomo asked for a reason.
"He doesn't respect his own presidency and frankly, at a deeper level, I don't think he respects himself," Buttigieg responded, accusing Trump of creating a "cartoon character" akin to a reality TV show.
"When you're the president of the United States, lives depend on your integrity, on your wisdom, on your judgment and I just don't see it in this White House," he argued. "I don't see any integrity there. You look at him and there is just a sense that he would do anything. This is a guy who's shown no evidence of any principle other than that of advancing himself and that is so costly right now."
Buttigieg accused the president of keeping none of his campaign promises except for tax cuts for the wealthy and conservative judicial appointments.
"None of the things he said he was gonna do are happening and moreover, I don't think any of the things he said he was gonna do are things he actually cares about," Buttigieg said.
Buttigieg's candidacy has picked up some steam in recent weeks, with pundits crediting him for a solid performance at the last Democratic presidential debate. A new poll this week showed him among the leaders in Iowa.
The Quinnipiac University poll released Wednesday showed 20 percent of Iowa voters support Sen. Elizabeth Warren, D-Mass., followed by 19 percent supporting Buttigieg, 17 percent for Sen. Bernie Sanders, I-Vt. and 15 percent for Joe Biden.