He pointed to charges filed in March 2016 against hackers linked to the Iranian government who allegedly launched attacks on U.S. financial institutions and on a flood-control dam north of New York City.
U.S. prosecutors also accused him of working for the Iranian military, carrying out cyberattacks on their behalf including on nuclear and Israeli infrastructure.
"Today's charges make clear that nation-states, like Iran, routinely employ alleged criminals, mercenaries, like Mesri, to conduct network attacks in America and elsewhere", Kim said.
After HBO apparently refused to pay, Mesri began leaking portions of the stolen material on websites he controlled, the indictment says.
As much as Mezri's crime was pretty outrageous we should consider the scale of subsequent crimes that were committed as a result of his and others work.The season seven premiere episode of Game of Thronessmashed TV rating records by the number of people that watched it.
"He will never be able to travel outside of Iran without fear that he will be arrested on these charges".
He is accused of compromising multiple user accounts, and in July of sending an anonymous email to HBO personnel saying: "Hi to All losers!" He then increased the ransom to $6 million. In July, he emailed HBO executives in NY providing evidence of the hack and demanding $5.5 million in digital currency, a figure later raised to $6 million, it says.
Behzad Mesri is accused of stealing data related to unaired episodes of HBO series including Game of Thrones and attempting to extort US$6m from the premium U.S. cablenet.
A spokesman with the U.S. Attorney's Office said that Mesri has not been arrested, but declined to comment on the suspect's whereabouts.
It is unclear if HBO paid any part of the ransom to the hacker.
During the cyber siege this summer, HBO worked with investigators and law-enforcement agencies and alerted "Game of Thrones" cast members, some of whom had their personal information exposed. On Monday, the Justice Department filed a lawsuit to attempt to block the $85 billion deal, a move which the companies have vowed to fight in court.