Pogba has entered the final year of his existing deal, although the club hold an option to extend until 2022.
The France international has been linked with a move away from Old Trafford but Raiola said he will not leave the club this summer.
"He is at the heart of the important project," he told Sky Sports Italia. "Even in previous years, United have never entertained offers."
Asked whether he is close a new contract, he added: "We are talking very calmly without any stress."
United boss Ole Gunnar Solskjaer also said he was confident that Pogba would sign a new deal.
The midfielder performed well alongside Bruno Fernandes after the Premier League restart and helped United achieve a top-three finish for only the second time since Sir Alex Ferguson's departure in 2013.
The striker's contract expired at the end of the campaign but Raiola is hopeful there is time to reach an agreement to keep the player at the San Siro.
"I don't believe he [Ibrahimovic] will join the Milan training camp tomorrow," he added. "While we are negotiating, we are at a good stage. We are talking, but not agreement as yet.
"It's not a money issue, but about conviction and style. A marriage is made successful with two people. If Ibra didn't want to stay, we wouldn't be negotiating, but we are."