Harper said Monday he was shocked the Marlins traded their entire outfield during the offseason. He added that Miami could have become a formidable team by adding a couple of pitchers.
Harper joined a chorus of critics questioning the direction of the Marlins under new CEO Derek Jeter.
Mattingly emphasized on Tuesday that it's important to "take care of your own dugout" and said it's "not really [Harper's] place to comment on us."
"He doesn't really know what goes on over here," Mattingly said. "He may think he does. But he doesn't know what the discussions are. He doesn't know our players."