It's been claimed the pair are not on speaking terms, with Isco upset over Ronaldo's support of direct rival James Rodriguez last season.
With Isco now establishing himself in coach Zinedine Zidane's starting XI, the midfielder is the team's leading goalscorer - which has put Ronaldo's nose out of joint.
"He considers that he opens spaces, gives assists and gives depth to the game. He believes that when the Bale is not on the field, the team's options are down.
"In addition, Cristiano is angry with Isco because he did not go to thank him for the assist against Las Palmas..."