Four days after hitting a moving ball at the U.S. Open, which cost him a two-stroke penalty and ignited a firestorm of criticism over his handling of the situation, Phil Mickelson on Wednesday apologized for his actions.

"I know this should've come sooner, but it's taken me a few days to calm down," Mickelson said in a statement. "My anger and frustration got the best of me last weekend. I'm embarrassed and disappointed by my actions. It was clearly not my finest moment and I'm sorry."

Mickelson rolled a downhill putt past the hole on the 13th green in Saturday's third round. Instead of waiting for the ball to come to a stop, Mickelson jogged toward it and hit it again before the ball had a chance to roll well past the hole and likely off the green. He was assessed a 2-stroke penalty and made a 10 on the hole en route to an 81, which matched his highest score ever in the U.S. Open.

After the round, Mickelson showed no regret about how he handled the situation and said he was simply taking advantage of the rules.

"I don't mean it disrespectful; if you're taking it that way, that's not on me,'' Mickelson said immediately after the round. "I'm sorry that you're taking it that way, it's certainly not meant that way. Sometimes in these situations, it's just easier to take the 2 shots and move on.''

Some called for Mickelson to be disqualified. He spoke with USGA officials after the round to discuss whether he should indeed play Sunday's final round.

"Phil really did want to understand how the rule operates because he didn't want to ... as he said to me, 'Mike, I don't want to play in this championship if I should have been disqualified,'" USGA chief executive Mike Davis said. "That's where we clarified that 'Phil, you make a stroke at a moving ball, so we have to apply that rule.'

"That's different than if he had deliberately just stopped the ball or whacked it in another direction or something like that. So it's just us applying the rules.''

Mickelson played Sunday, shooting 1-under 69, including a par at the 13th hole.

On Tuesday at the Travelers Championship in Cromwell, Connecticut, Jordan Spieth said he understood the position of those who criticized Mickelson, but he also believes Mickelson meant no disrespect to the game and its rules.

"Phil knows the rules," Spieth said. "If there was a chance it was going to go back behind the bunker and he's got to chip back or he was going to play off the green anyway ... so he was potentially saving himself a shot. So if that was the intent, then what's the harm in that? He's playing for the best score he can.

"I don't think people thought that was the intent, but I'll take his word it was his intent. He knows the rules."

Rory McIlroy, who along with Spieth was paired with Mickelson for the first two rounds at Shinnecock Hills, also said it was blown out of proportion.

"Honestly, I laughed [when I heard about it]," McIlroy told reporters on Wednesday. "I felt it was a massive overreaction to it. Phil knew what he was doing. Look, as a player who has been in that headspace at that tournament, I can see it happening to people.

"It's a tournament that Phil has come so close to winning over the past few years. He's probably seen what's happened over the past few years at that tournament and it's frustrated him because it's the only [major] he hasn't won. Plus, it's probably becoming the hardest one to win for anyone because it is a bit of a lottery at times. I don't know if I'd go to the lengths he went to make a statement like that, but I felt there was a massive overreaction to it."