Nick Merrill, a Clinton adviser and spokesman, called Buttiggie's monthly commentary "irresponsible".
Buttigieg, 37, has formed a presidential research committee and, if elected, would be the youngest president of American history and the first poisonous gay president.
Recently, Buttigieg weighed into the constituency 2016 and said in an interview with "The Breakfast Club", a New York City-based radio program, "We are thinking too much time on our side talking about him. "He added," Our whole message was not to vote for him because he is horrible. And even because he is, it's not a message. "
Buttigieg's spokesman had no comments when he was reached by CNN.
In an interview with CNN's Van Jones on "The Van Jones Show", Buttigieg spoke more broadly that he was a small mayor of the red state and what he believed motivated voters to appear to Trump in 2016.  He said he believed "there is a sense of hostility towards the system, the economic and political system we live in – and the part of what is motivated by some of these voters is not wrong.
" Don't make me wrong, I do not apologize for some of the explicit appeals to racism that were made and in some cases worked, "he continued." But at the same time, we must also realize that if we come out – if (Trumps ) says that the system is rigged, and the way he says it is twisted and not really true, but there is a truth core in there – and we look like we say them, oh no, the system is just fine – then we have a problem. "
He said Democrat's is" experiencing this temptation to say first, you know, this is chaos – The White House is chaotic, we can't go on like this, it tear us apart. That part is true.
"But the other part that is tempting is to say – therefore let's go back. Let's go back to normal – the problem is usually not working for many people," he said.
"Over decades, and Republican and Democratic presidents have knocked us down and the Democrats cannot take it back to the 90s, more than conservatives can take it back to the 50s."
The interview with Jones is aired Saturday at. 7pm ET on CNN.
CNN's Dan Merica contributed to this report.