The 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 illness
The coach stayed on at Camp Nou last season despite suffering a relapse of his throat cancer in December 2012 following surgery the year before, but he has opted out of continuing in the position in 2013-14 in order to pursue further treatment.
Iniesta, whose inspired performances last season under Vilanova helped Barca to the Liga title, is hoping that 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 am 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."
Barca left-back Jordi Alba, who was signed under Vilanova's reign, was 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."