The Celtic boss confirmed on Friday that the Scottish champions had rejected an offer, reported to be about £5million, from the Canaries for the 24-year-old Englishman, who showed why he is attracting attention from south of the border when he slid in an Adam Matthews cross in the second minute.
Georgios Samaras added a second 10 minutes later, but after Jason Holt pulled a goal back in the 68th minute there was a nervy spell for the home side which only ended five minutes from time when Hooper grabbed a third to make it 20 for the season.
Substitute Lassad Nouioui, on for Matthews, made it four in added time to maintain Celtic's nine-point lead over Inverness at the top of the Clydesdale Bank Premier League.
Lennon, who is hoping to keep his squad intact for next month's Champions League last-16 clash with Juventus, said: "I thought Gary was brilliant, he was at his best. He got two goals, but I think his all-round game was top class.
"We had a chat last night after speaking to his representatives and we wanted to make our position clear to him and he is quite comfortable with it all.
"We have made it clear that we are not selling him, we don't want him to go, especially at this juncture of the season. However, everyone has their price and what Gary's price is will be down to the board and myself to decide.
"What we were offered on Thursday was nowhere near our valuation of the player.
"We don't have a set figure, however, goalscorers are at a premium and Gary is a goalscorer so we will set the bar pretty high for him.
"I am hearing that they (Norwich) might come again but good luck to them on that."