The company said in a posting on its PlayStation blog that no personal information of the network was accessed in the attack, which overwhelmed the system with heavy traffic.
"We will continue to work towards fixing this issue and hope to have our services up and running as soon as possible," it said.
A plane carrying Sony Online Entertainment President John Smedley was diverted on Sunday, Smedley said in a post on microblogging site Twitter.
A group called Lizard Squad sent a message through its Twitter account to American Airlines saying Smedley's flight had explosives on board, according to a report by USA Today. The group also used Twitter to claim credit for the network attack, the newspaper said.
USA Today reported that the Dallas/Fort Worth flight to San Diego was diverted and landed safely in Phoenix.
A PlayStation spokeswoman in the United States said the diverted flight was being handled by the FBI and had no comment. An FBI spokesman had no immediate comment.
Sony is hoping its PlayStation network, with 52 million active users, can serve as a centerpiece of its plans to rebuild its business after years of losses in its flagship electronics operations.
The network business has been hit by attacks before, with a security breach in 2011 dealing a major blow to plans at the time for a looser network designed to allow for the connection of a range of Sony devices.