(Adds more Obama comments, background)
WASHINGTON, Dec 21 (Reuters) - U.S. President Barack Obama does not consider the cyber attack on Sony Corp to be an act of war, he said in an interview, remarks apparently aimed at limiting U.S. anger over the incident which Washington blames on North Korea.
Obama and his advisers are weighing how to respond in kind to the attack, which prompted the Hollywood studio owned by the Japanese firm to withdraw a comedy, "The Interview," prepared for release to movie theaters during the holiday season.
"No, I don't think it was an act of war. I think it was an act of cyber vandalism that was very costly, very expensive. We take it very seriously. We will respond proportionately," Obama told CNN's "State of the Union with Candy Crowley" show, which was taped on Friday and due to be aired on Sunday.
North Korea has denied responsibility for the attack on Sony. The film depicts the fictional assassination of North Korean leader Kim Jong-un.
Obama also said his government was considering putting North Korea back on a U.S. list of countries that sponsor terrorism. It was removed from the list six years ago.
Obama told a White House news conference on Friday that he believed Sony made a mistake by withdrawing the movie in response to the hack of its computer networks.
Sony CEO Michael Lynton has said in response that Sony had no choice but to cancel the film's release because major theater chains refused to show it.
In the CNN interview, Obama said he was sympathetic to Sony's business considerations but stuck to his argument that the entertainment company had made a mistake.
"Had they talked to me directly about this decision, I might have called the movie theater chains and distributors and asked them what that story was," he said.
Obama said an important free speech principle was at stake.
"If we set a precedent in which a dictator in another country can disrupt, through cyber, you know, a company's distribution chain or its products and, as a consequence, we start censoring ourselves, that's a problem," he said.
He called on the U.S. Congress to pass a cyber-security law.
"We've got to work with the private sector and the private sector has to work together to harden their sites. But in the meantime, when there's a breach, we have to go after the wrongdoer. We can't start changing how we operate," he said.
(Reporting by Steve Holland; Editing by Peter Graff)