Celtic dismissed a £5m bid from Norwich for the Englishman, who took his season's tally to 18 with a double in the 4-1 victory over Hearts on Saturday.
As well as attracting the attention of potential suitors - Hooper's form in the Champions League, along with team-mate Fraser Forster, has been noted by England coach Roy Hodgson, who has already included the Celtic goalkeeper in his squad.
But the Hoops boss stressed it will take an exceptional bid for Celtic chief executive Peter Lawwell to consider allowing Hooper to leave.
"Everyone has their price and what Gary's price is will be down to the board and myself to decide," Lennon said. "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. He is at a big club as it is and he is in the Champions League.
"His ambition possibly is to play in the Premier League and I think he is good enough to do it now, there is no question about that.
"It just depends on the level he wants to play at and I don't think he is far away from international level as well. I mentioned him to Roy last week and he said he is keeping tabs on the two boys so it's all good.
"I am not going to stop any of the guys' progress because I wouldn't have wanted that done to myself, but I am the manager of the club and they have to do what Peter Lawwell and I think is best for the club's interests and, in the short term, it is keeping Gary Hooper here.
"But we still have two weeks to go of the transfer window and the last week gets pretty heavy. I am sure he is on the radar of plenty of clubs."