Hooper has bagged an impressive 63 goals in 90 Scottish Premier League starts for the Glasgow giants following his £2.4milllion signing from Scunthorpe in July 2010.
That has inevitably led to interest in his services, and while Lennon does not want the 25-year-old to depart, he accepts the Scottish double winners may not be in a position to reject a big-money offer.
He told Sky Sports News: "He is a pivotal player for us, he is a masterful player, he has really developed into a top-class striker.
"It is a back-handed compliment to the work that has been done behind the scenes at the club and developing Gary as a player.
"He is a brilliant young English player, we would love to hold onto him, it is a priority for me to hold to him, but if we get a bid in that is good business for the club we may have to think again."
Goalkeeper Forster joined Celtic on a permanent deal last summer for £2.5million after spending the two previous campaigns on loan with the Bhoys from Newcastle.
He recently hinted that he would consider a move away to further his international ambitions as he targets a place in Roy Hodgson's squad ahead of the 2014 World Cup.
But Lennon, who was also keen to play down suggestions Victor Wanyama could be set to depart, stressed that Forster, like Hooper, is integral to their future plans.
Lennon added: "We signed him in the summer, he is not going anywhere. He made his name at Celtic and has gone from third choice goalkeeper at Newcastle to third choice goalkeeper for England in a very short space of time.
"He is a wonderful talent, we think there is more to come from him.
"That will be the same for all the players. If the deal is right for the club and makes good business sense then we will consider that.
"There have been no real concrete offers on the table since the end of the season for anybody yet. There is speculation, but nothing concrete.
"You don't want to see your best players go, but everyone has a selling point and we're no different to anyone else."