"The result of investigation by FBI is so excellent that you might have seen what we were doing with your own eye," said the statement posted on the file-sharing website pastebin. "We congratulate you (sic) success. FBI is the BEST in the world. You will find the gift for FBI at the following address. Enjoy!"
The link provided in the message leads to a YouTube video titled "You Are An Idiot."
The FBI declined comment on the message.
The FBI announced Monday North Korea is responsible for the cyberattack on Sony Pictures. An FBI investigation linked the malware, infrastructure and techniques used by the Guardians of Peace in the Sony attack to previous North Korean cyberattacks.
The hackers broke into Sony's servers, published private emails and information, and threatened to attack movie theaters screening "The Interview," a comedy film about an assassination plot on North Korean leader Kim Jong Un.
Earlier Saturday, North Korea slammed U.S. claims that the regime is responsible for a cyberattack on Sony Pictures -- and then proposed the two countries work together.
"Whoever is going to frame our country for a crime should present concrete evidence," the state-run Korean Central News Agency reported.
"America's childish investigation result and its attempt to frame us for this crime shows their hostile tendency towards us."
But in a rare move, the North Korean regime said both countries should work together.
"While America has been criticized by its own public and continues to point the finger at us, we suggest mutual investigation with America on this case," KCNA said.
"If America refuses our proposal of mutual investigation, continues to link us to this case, and talk about actions in response, they (America) will be met with serious consequences."
U.S. Replies to North Korea
National Security Council spokesman Mark Stroh replied to the North Korean statement:
"As the FBI made clear, we are confident the North Korean government is responsible for this destructive attack. We stand by this conclusion. The government of North Korea has a long history of denying responsibility for destructive and provocative actions. If the North Korean government wants to help, they can admit their culpability and compensate Sony for the damages this attack caused."
U.S. President Barack Obama said that Sony Pictures made a mistake in canceling the release of the movie.
"I am sympathetic to the concerns that they face," Obama said. "Having said all that, yes, I think they made a mistake. Let's not get into that way of doing business."
North Korea rejected the notion that it would attack "innocent moviegoers."
"We will not tolerate the people who are willing to insult our supreme leader, but even when we retaliate, we will not conduct terror against innocent moviegoers," KCNA said.
"The retaliation will target the ones who are responsible and the originators of the insults. Our army has the intention and ability to do (so)."
Analyst: We underestimated North Korea
The show may go on
Sony Pictures Entertainment CEO Michael Lynton rebuffed Obama's criticism in an interview with CNN's Fareed Zakaria, saying his company did not make a mistake.
He said the decision to pull back from the planned December 25 release was based on major movie theater companies telling Sony that they would not screen the film.
"We have not caved. We have not given in," Lynton said. "We have persevered, and we have not backed down. We have always had the desire to have the American public see this movie."
And despite enduring what he called "the worst cyberattack in American history," Lynton said his studios would make the movie again. But in retrospect, he may have "done some things slightly differently."
A defiant Sony scrambles to find a way out for 'The Interview'