Warmbier died last Monday of severe brain damage in a Cincinnati hospital and was buried three days later.
The Asian country has denied torturing Warmbier.
Warmbier was imprisoned for reportedly trying to steal a North Korean propaganda poster.
He was sent home last week suffering from brain damage and in what US doctors called a state of unresponsive wakefulness.
It is the first official comments by the country on the state in which it returned Warmbier to his family. "The fact that Warmbier died suddenly in less than a week just after his return to the U.S.in his normal state of health indicators is a mystery to us as well", a Foreign Ministry spokesman said in a statement released Friday.
This comment seemed to echo President Donald Trump's sentiments on Warmbier's death, which he issued in a statement from the White House on Tuesday.
Gargash: Gulf states don't seek Qatar 'regime change'
Saudi Arabia demanded Qatar change its policy, in order to adjust Al Jazeera's broadcasting to the interests of the Gulf States. The move by Qatar's neighbours has left it under a de facto blockade. "The alternative is not escalation", he said.
Warmbier was a native of Wyoming, Ohio and a student at the University of Virginia.
"It ain't about trying to release people", he said.
A spokesperson for North Korea said that the rogue nation did provide medical treatment for Warmbier and that the accusations against the North are "groundless" speculation.
"The smear campaign against DPRK staged in the USA compels us to make firm determination that humanitarianism and benevolence for the enemy are a taboo and we should further sharpen the blade of law", the statement read.
North Korea accepted repeated requests from the present US administration, the spokesman said, and repatriated the student on humanitarian grounds "in consideration of his bad health".
According to the statement, North Korea does not know the cause of Warmbier's death.
"I'm going over there out of the kindness of my heart just to try to help", Rodman said, breaking down.
"I was just so happy to see the kid released", Rodman said about the day he heard Warmbier was being released in an interview on Good Morning America. "Some good things came of this trip". Is there anyone dumb enough to think Wambier received better treatement at the hands of North Korea prison doctors than he did here at home.