Goodell also said he'd be willing to meet with Sen. Arlen Specter, who sent a letter to the commissioner the previous day asking why tapes shot by the New England Patriots in the cheating scandal were destroyed.
"The reason I destroyed the tapes is they were totally consistent with what the team told me," Goodell said during his State of the NFL speech. "It was the appropriate thing to do and I think it sent a message.
"The actual effectiveness of taping and taking of signals from opponents -- it is something done widely in many sports. I think it probably had limited, if any effect, on the outcome of games.
"That doesn't change my perspective on violating rules and the need to be punished."
NFL security confiscated a video camera and tape from a Patriots employee during New England's 38-14 victory over the New York Jets in the season opener. The employee was accused of aiming his camera at the Jets' defensive coaches as they signaled to players on the field.
Goodell fined Belichick $500,000 and docked the team $250,000 and a first-round draft pick. It was the biggest fine ever for a coach and the first time in NFL history a first-round draft pick has been confiscated as a penalty.
Goodell said there were six tapes, some from 2007 preseason games and the rest from 2006. Another reason he destroyed them was one tape was leaked to the media just after the Patriots-Jets game.
"We wanted to take and destroy that information," he said. "They may have collected it within the rules, but we couldn't determine that. So we felt that it should be destroyed."
Specter, the top Republican on the Senate Judiciary Committee, said the issue could put the league's antitrust exemption at risk.
The matter may not compare to the CIA's destruction of interrogation tapes, Specter said in a Capitol Hill press conference, but the Pennsylvania senator added, "I do believe that it is a matter of importance. It's not going to displace the stimulus package or the Iraq war, but I think the integrity of football is very important, and I think the National Football League has a special duty to the American people -- and further the Congress -- because they have an antitrust exemption."