WASHINGTON — A White House official said on Thursday that the administration was considering a “proportional response” against those who hacked into Sony Pictures computers, a retaliation that could thrust the United States into a direct confrontation with North Korea.

Officials would not describe what such a response might entail, but they stressed that the episode had become a major concern at the upper levels of government, including President Obama, who lately has been discussing the issue with aides every day.

“This is something that’s being treated as a serious national security matter,” Josh Earnest, the White House press secretary, told reporters. “There is evidence to indicate that we have seen destructive activity with malicious intent that was initiated by a sophisticated actor.”

United States officials have privately concluded that North Korea was “centrally involved” in the hacking even as Sony canceled the release of a comedy that features the fictional assassination of the North Korean leader, Kim Jong-un, and that apparently prompted the cyberattack. Mr. Earnest would not confirm the North Korean role at his daily briefing but he did not deny it either, saying that investigators would ultimately report on their findings.