The Spain midfielder admits it is "fateful news" that the goalkeeper will likely miss the World Cup and not play for Barcelona again after rupturing a knee ligament
Valdes was stretchered off during his side's 3-0 win over Celta on Wednesday, with tests later confirming he has suffered a ruptured ligament to his right knee, meaning he faces a lengthy spell on the sidelines.
With the 32-year-old set to leave Camp Nou when his contract expires this summer, it would seem he has played his last game in a Barcelona shirt, and team-mate Iniesta admits it is a major blow.
"For him, for the situation, for those who came to the game today... it is fateful news," he told Barca TV.
"The important thing now is that he recovers well, and that we give him all our support. He has all of our affection.
"These things happen in football and sport. To play every Sunday and Wednesday, for the good or the bad, gives you no time to savour things or to complain. That's why we're Barca, we're mentally prepared to live such extremes."
Two goals from Neymar and a solitary strike from Lionel Messi handed Barca a comfortable win on Wednesday and Iniesta - who set up Messi's goal with a precision pass - was quick to praise the almost telepathic understanding he shares with the Argentine.
"You understand everything with Leo. We've known each other for a long time, we know each other's capabilities. Although he's not looking, he knows I can make that pass for him," he said.
"We've got back into the fight for the league on merit. There is a month and a half left in the competition and we are in the fight for everything. It's still the most beautfiul and the most difficult competition.
"[The Clasico win] gave us an important morale boost. Every game is now a final."
With Barcelona now just a point behind Atletico Madrid at the top of La Liga, Iniesta is relishing the prospect of facing Espanyol in the derby clash on Saturday.
"The derby is more than just a match. It's very special for us and for them, and also for the current situation in the league," he added. "We go there to win, as always."