The 21-year-old Iheanacho, who was signed from Manchester City in 2017, has scored 8 goals in 28 appearances for Leicester City.
"It's a difficulty but my first feeling was that it is unbelievable for this player to show their quality and it's good publicity for Leicester", said Puel, who feels Maguire now has the confidence that he belongs on the world stage.
British media have reported that Jose Mourinho's United could be set to launch a world record bid for a defender on the back of Maguire's impressive World Cup campaign in Russian Federation where England reached the semi-finals for the first time in 28 years.
Ferdinand admits he would love to see France World Cup champion and multiple Champions League victor Raphael Varane at Manchester United.
Manchester United are rumoured to want a new centre-back and Harry Maguire would quite happily fit the bill for Jose Mourinho - who is widely expected to bring one of Maguire, Jerome Boateng or Toby Alderweireld to Old Trafford in the forthcoming 24hrs.
Both players were in action on Friday night as Leicester opened their season with a 2-1 defeat to United at Old Trafford, and Chilwell also paid tribute to his teammate's performance.
"We all know what Harry is capable of, we all know how good he is".
But as far as Leicester are concerned, Maguire is not for sale.
"We have another training session this afternoon and then we will make decisions about the squad".
Maguire will be in the Leicester squad for tomorrow's Premier League opener at United and Puel joked: "I can confirm he is going..."
He said: "I was happy with the progress of Harry in the second half of last season". We saw that again tonight, how good a player he is.
"He is going to be good for us".