The Coach resigned from his duties at Camp Nou on Friday evening after the club confirmed he was diagnosed with a second bout of throat cancer.
Argentine forward Messi has insisted that the whole squad are behind the former boss.
“Stay strong, Tito!” he posted on his official Facebook page. “We’re right behind you in this battle!”
Midfielder Iniesta also believes that the tactician will come out fighting.
“Tito will once again win this terrible battle facing him,” he said.
“On behalf of the players and everyone, I send him all my love and support.
“At the end of the day, this is about a person, not a Coach.”
Real Madrid boss Carlo Ancelotti said that he was sad when he heard the news.
“I want to send a message of support and encouragement to my colleague Tito,” he said.
“I’m sad about the news, but he’s a fighter. I want to tell him that the whole squad and the club are with him.
“We hope that everything turns out well for him.”