The Northern Irishman is in no rush to sell his star striker, after the club rejected a £4.5 million bid for the 25-year-old, who has just one year left on his contract
Hull City are thought to have had a bid of around £4.5 million turned down by the Scottish champions, while Norwich, Southampton and Sunderland have also reportedly expressed an interest in the striker.
However, the Bhoys are in no rush to sell the 25-year-old, despite just one year remaining on his current contract.
"We had a bid from Hull City which we rejected,” Lennon told Sky Sports. “Whether they come again, I don't know. As you were.
"No set price. The offer made was well below our valuation of player. We would be very happy for him to stay and if he decides to stay on, contract negotiations may re-open again.
"He will come to Germany on Monday and will be part of our plans for [Champions League] qualifers."
The Northern Irishman is also hoping to retain the services of striker Anthony Stokes, who is currently out of contract at Celtic Park.
"He rejected an earlier offer around May time but we are hopeful we will get across the line with Anthony,” he continued.
"He is a player we would like to keep."