Barca's title was confirmed with victory at Deportivo La Coruna.
"It's an indescribable feeling, on a personal level and as a sportsperson, there are no words when you receive so much love from people and even more so in difficult moments for them [as Deportivo were relegated]," Iniesta confessed.
"It's an eternal thank you, because it's very beautiful.
"This [move] isn't a change of opinion, but I am making the most honest decision for myself and my club.
"To finish the season with these feelings before the World Cup and with another adventure ahead, I wish it were eternal. I would like this to never end, but everything has its beginning and its end."
Iniesta also addressed questions on his future, though he would not be drawn on what lies ahead for him.
"I still don't know, nothing is done, when the season is done hopefully everything will be in order," he insisted.