Warmbier's parents have hinted they were disappointed by the Obama administration's response to Warmbier's disappearance.
Justin Weber said that a press conference is expected later to provide details. The company says the "tragic outcome" of Warmbier's trip - the American died after being jailed and had been in a coma - prompted the change.
The tour group Otto Warmbier used to travel to North Korea will no longer allow Americans to participate in tours to the country, a decision the group said it came to after Warmbier's death on Monday. They said it should be a "call to action to those in the position to protect our American citizens here at home AND overseas".
"Yes, this had happened while Mr Warmbier was in the detention of North Korean authorities", Moon told CBS.
In a separate note from Seoul's Blue House, Mr Moon was quoted saying: "It is very deplorable that North Korea does not respect human rights". "And frankly, if he were brought home sooner, I think the results would have been a lot different", the president said.
Warmbier is a smart and immensely likable kid who graduated from high school in 2013 in his hometown of Wyoming, Ohio, and enrolled in the University of Virginia.
His parents, Fred and Cindy Warmbier, said in a statement that he died surrounded by loved ones at 2:20 p.m. on Monday.
Spicer did, however, say the administration has been working with China to help improve America's relationship with North Korea - a reclusive nation that is developing nuclear weapons.
Warmbier was "generous, outgoing, sweet, smart as a whip, just an overall good guy", Danica White, his sophomore English teacher, recalled last week.
"We hold North Korea accountable for Otto Warmbier's unjust imprisonment, and demand the release of three other Americans who have been illegally detained", said Tillerson in a statement on Monday. He said his son was a "thrill seeker" who wanted to see North Korea. He was sentenced to 15 years of hard labor in prison, but was released in June, 17 months after his arrest, in a coma.
The tour operator said that it was denied any opportunity to meet with Warmbier after his detention, and that the way it was handled was "appalling".