The veteran was disappointed to see Rangers’ leading striker refuse to shake hands at the end of Livingston’s 1-0 victory over Steven Gerrard’s men on Sunday.
This came after defender Declan Gallagher was criticised for taunting his Rangers opponents after the full-time whistle.
Gallagher, however, insists he only did so after members of the away side refused to shake his hand. This has since been backed up by his older team-mate.
“It was disgraceful from Morelos on Sunday,” said Miller. “It was so unprofessional as well.
“I really feel for big Declan. He’s been made out to be the bad guy. Don’t get me wrong, Morelos is a quality act as a player.
“It’s testimony to him that people are trying to mark him out the game and make things difficult for him.
“But he’s got to take it and show respect by shaking hands at the end of the game. That part of it he lacked.
“To be fair, he wasn’t the only Rangers player and [Daniel] Candeias refused to shake hands as well.”