"It's not my fault he didn't get selected," Sanchez said through an interpreter.
Morrison has 24 home runs this season, tied for second in the majors, but he didn't get an invitation. Sanchez has 13 home runs in an injury-shortened first half and is competing in Monday's event.
"Gary shouldn't be there,'' Morrison told the Tampa Bay Times on Tuesday. "Gary's a great player, but he shouldn't be in the Home Run Derby.
"I remember when I had 14 home runs. That was a month and a half ago."
Sanchez will join his Yankees teammate, rookie Aaron Judge -- the overall leader in home runs with 28 -- Kansas City's Mike Moustakas and Minnesota's Miguel Sano on the four-man team that will represent the American League.
"What can I say?" Sanchez said. "They gave me a call, gave me an invitation to participate."
Morrison said Wednesday that his comments weren't about Sanchez.
"People can read it and say he's jealous of Gary because he got picked, but it's not about that,'' Morrison said before Tampa Bay's game in Chicago against the Cubs. "Eric Thames got slighted, too. How is that guy not in the Home Run Derby for the National League? It's a flawed system.''
Sanchez has the fewest homers among those competing, but he missed more than a month of the season because of a strained biceps.
Sanchez did have one stipulation for participating in the derby.
"I told them, 'I don't even know if I'm making the All-Star Game,'" Sanchez said. "If I make the All-Star Game then for sure I'll do it. It's an honor to participate in the event. It's not my fault he didn't get selected. Like I said before, I'm just happy to participate and it will be an honor to be part of it."
Morrison might get a chance to go to the All-Star Game. Although he wasn't chosen for the AL team, he is on the five-man ballot for the final spot on the squad.
The Associated Press contributed to this report.