Hooper has so far refused to put pen to paper on a contract extension – and several Barclays Premier League clubs are monitoring his situation.
Liverpool, Newcastle United and Sunderland have all been linked with the English hitman, who has netted 13 times in the 2012/13 campaign.
However, Lennon is optimistic making it to the last 16 of Europe's premier club competition will convince him to prolong his stay at the Scottish champions.
The 24-year-old banged in the first goal in the 2-1 win over Spartak Moscow at Parkhead to ensure the Hoops finished second in Group G.
Lennon said: "Why would players leave just now when they have something so special to look forward to? There aren't many clubs that can offer that. I'm pretty sure we won't be selling anyone. Gary's representatives are up again this weekend and we are hopeful we can get something done on a positive note there. There is obviously no guarantee, but we are hopeful."
Lennon is also optimistic an agreement can be reached with Victor Wanyama, who is under contract until 2015, after making it to the knockout stages of the Champions League.
He said: "We will keep plugging away with his representatives and see if we can come to a conclusion that pleases everybody."
Meanwhile, Lennon has revealed he is set to hold talks with Scott Brown about the midfielder's ongoing hip problem.
The midfielder, who lasted most of the game against Spartak, is keen to play on without undergoing surgery on the persistent complaint.
However, the 27-year-old would be fit for the last 16 of the Champions League in March if he underwent the operation now.
Lennon said: "He's feeling good and remarkably again had a great game for us the other night. He doesn't want to have the surgery so we are going to manage him the best we can.
"We can't force him to have surgery, although eventually our medical team thinks he will require it. It's not like we are soft-soaping him through training now, he is training all the time.
"He has obviously had a positive reaction from the last injection and we will just keep going.
"We need to chat about it. If and when the surgery is required we will need to plan the period he is going to be out, because we would like him for the last 16.
"I don't think he would miss the last 16 if he had it now. It's an eight-week period of rehab.
"I haven't really had a chance to speak to him or my medical team, but he wants to keep on playing. But we don't want to put him through what we put him through the last two months."
Kris Commons (thigh) and Mikael Lustig (hamstring) will both miss the match with Kilmarnock at Rugby Park today after picking up injuries in midweek.