The Spain midfielder has backed the 44-year-old to make a full recovery while team-mate Jordi Alba admits he is in the dark over the severity of his former coach's illness
Vilanova stayed on at Camp Nou last season despite suffering a relapse of his throat cancer in December 2012 but has elected not to continue in the position ahead of the coming campaign to pursue further treatment.
And Iniesta, whose inspired performances last season under Vilanova helped Barca to the Liga title, hopes the 44-year-old can recover from his health problems in the near future.
Speaking at a statue unveiling in his hometown of Fuentealbilla, Iniesta said: "For me this is a day of contrasts: I’m excited about this homage I have been given, but it’s a very tough day with the news about Tito.
"The person is the most important thing and I just hope this is sorted soon. Tito will fight back and win this terrible fight."
Meanwhile, Barca left-back Jordi Alba, who was signed under Vilanova's reign, admits he is in the dark over exactly what is wrong with the coach but hopes that he fights back swiftly.
"I don’t know anything and it has taken me by surprise," he is quoted as saying by latdap.ct. "If it’s true, it’ll be a very bad piece of news.
"He’s done a great job and we hope he gets well soon and comes back."