Elliott visited the store Thursday a few hours before the Cowboys played the Seattle Seahawks.
"I don't this it was a good decision," Garrett said, "He and I talked about that. It was just a poor decision on his part and young players sometimes just have to understand that perception can be reality.
"You have to understand you're under a microscope 24 hours a day, and there's no good reason for him to go into a place like that."
Elliott, the fourth pick in the NFL draft, gained 48 yards on seven carries. He's not expected to play Thursday against the Houston Texans in the final preseason game.
"He apologized," Garrett said of Elliott. "He recognized his mistake and it's something he'll learn from."