Puig, who arrived 45 minutes after stretching began and several hours after most of his teammates, said he "didn't know" the time for stretching was moved up because of Opening Day ceremonies. He was asked if he received the text message Mattingly said the club sends as a reminder.
"Whether I received it or not doesn't matter," he said. "This is my fault. I made a mistake. I don't blame anyone."
Puig said Mattingly made the "right decision" taking him out of the starting lineup and he would "make sure I stick with the schedule." He said he was "disappointed" to miss the team's home opener and asked fans to forgive him.
"I'm truly sorry," Puig said.
"It's a mistake, and we move on," said Mattingly. "It can happen very easily. I don't feel it's a huge deal for us. He was humbled. He truly felt bad. His body language, he doesn't hide it very well. He had the right disposition, but that didn't change what we had to do."
Mattingly said he would have used Puig to pinch-hit if the right situation had come up.
Puig said he apologized to Mattingly and the team in the latest of an ongoing series of issues. Only last week, Puig was nearly late for a workout, triggering a meeting called by Mattingly to address the outfielder. Mattingly also had expressed exasperation with Puig while in Australia.
Puig has been high maintenance since the Dodgers signed him for seven years and $42 million out of Cuba. He was benched last year for arriving late to a game, was removed midway through a game for not hustling and has been arrested twice for speeding.
The latest incident benefited Kemp, who was originally annoyed when told he would not be in the starting lineup.
"Matt was upset. Matt wanted to play," Mattingly said.
For the home opener against right-hander Ryan Vogelsong, Mattingly originally was going to go with Carl Crawford, Andre Ethier and Puig from left field to right.
After scratching Puig, Ethier was moved to right and Kemp, batting second, to center.
Mattingly said the original lineup was a "one-day thing" and indicated Kemp would start Saturday against lefty Madison Bumgarner.
"I want to get him back in the mix without throwing him straight into the fire," Mattingly said.
He added that he will juggle the four outfielders by looking for the best matchups with opposing pitchers.
"It's not a perfect scenario by any means for anybody," he said.
But management saw last year that keeping all four outfielders healthy is no easy task. The club also has seen a supposed surplus of starting pitchers get tested two straight Aprils because of injuries.