"I tried to find him after the game to apologize, to let him know I'm not that kind of player who's trying to hurt guys and maliciously take violent hits at people," Looney said Monday, according to CSNBayArea.com. "I've been injured myself. I know what it's like."

The NFL reviewed the play and determined the block was not illegal. The Vikings registered a complaint and said Looney should be subject to discipline for the block, which resulted in a hyperextended knee, bone bruise and postular capsular strain for Williams.

An MRI, however, showed that Williams avoided ligament damage. His MRI is being forwarded to Dr. James Andrews for a second opinion.

An NFL spokesman said Dean Blandino, the league's vice president of officiating, determined Looney's block was legal under the rules and was not a violation of a new rule on peel-back blocks.

Vikings defensive end Jared Allen said Tuesday that it was "absurd" that Looney's block was declared legal.

"He had a perfect opportunity to hit him in the chest, but he intentionally went to his knee," Allen said. "We want to talk about protecting player safety and all that stuff? Well, I got fined for a hit up high [against Chicago last year] because they said I launched into a guy, right? If he hits Kevin in the chest, and something happens, that's part of it. But if you intentionally duck, and go to a guy's knee, I mean, it had no bearing on the play.

"You talk about player safety and wanting to protect us; how is Kevin not a defenseless player? It's just not what you do."

Vikings coach Leslie Frazier said Tuesday he talked to the NFL about the play and was told the league agrees that "it's not the type of play they want in the game for player safety reasons."

"I understand the rule. But I know it's going to be looked into further. That's not the type of play that any of us want to see," he said.

Vikings linebacker Chad Greenway wasn't as diplomatic about the play on Tuesday, blasting Looney's actions.

Joe Looney says he wasn't trying to hurt Kevin Williams with his low block Sunday. The NFL has said the play wasn't against the rules. Michael Zagaris/San Francisco 49ers/Getty Images

"It's really quite ridiculous," he said. "It's something we talked about in our meetings with the refs before the preseason started. It's just unnecessary. [Williams] wasn't going to make the play. He wasn't going to be part of the play. I understand that guy [Looney]'s trying to earn a job, as well, but he could have easily just hit him high.

"You can say what you want about you didn't mean to hurt him, but the reality is, you did that. And now we have a guy who's been one of the best at his position for a long time dealing with an injury he shouldn't have to deal with."

Allen said the NFL's emphasis on player safety amounted to a lot of empty talk in this case.

"I have a problem when we talk about player safety in this league, and we have a clear case of a guy trying to hurt a guy, and we do nothing about it. We pat them on the back and say it's OK," he said.

The 22-year-old Looney, who was picked by the 49ers in the fourth round of the 2012 draft, said he was "just trying to finish my block."

"I'm not out on the field trying to hurt anybody. I hope Kevin is all right," Looney said, according to CSNBayArea.com. "I was just trying to do what I was coached and play 100 percent to the whistle. I'm just trying to make the football team."

Williams walked off the field on his own after the block from Looney.

"I was just upset that I'm getting cut 11 years in [the NFL] from a guy who I don't even know," Williams said Sunday, according to the Star Tribune. "I figure between the pain and the fact he cut me when I wasn't looking was my reaction."

ESPN Senior NFL Insider Chris Mortensen and ESPN.com Vikings reporter Ben Goessling contributed to this report.