Pogba, who left United for free to join Juventus in 2012 at the age of 18, returned to Old Trafford in a world record 105m euro deal earlier this summer.
But Raiola told Rai Sport: “Paul could have left (Juventus) last year because (Jose) Mourinho – then at Chelsea – really wanted him.
“But Juventus and I had agreement: win the league title and the Champions League, then he can go.”
Juventus claimed a record-equalling fifth consecutive Serie A title last season but their progress in the Champions League was ended at the quarter-finals stage by Bayern Munich.
Raiola, meanwhile, said Pogba can expect a present from Napoli president Aurelio De Laurentiis because his transfer to United prepared the way for Juve to buy striker Gonzalo Higuain from Napoli for 90m euros.
He added: “De Laurentiis should be giving Paul a present, because without his departure Juventus would never have bought Higuain, and he would never have been able to bank all that money.”