The SPL champions booked a spot in the knockout phase of the Champions League on Wednesday after a 2-1 home win over Spartak Moscow secured the runners-up spot behind Barcelona.
Celtic's progression will generate further income, but Lennon is not planning to go overboard in the January transfer window if he tries to add to his squad.
"I do not want to spend mega-money on one player because that will only disrupt the spirit here," Lennon told The Times.
"There are positions we would like to strengthen, but whether we will do it or not is another thing."
Lennon will also be hoping to retain his key players, with the likes of striker Hooper and midfielder Victor Wanyama regularly linked with a move to the English Premier League.
The Celtic boss is anticipating further interest in his players in the New Year, but is optimistic he can retain his influential performers.
He added: "Hooper is someone I hang my hat on because he is a goalscorer.
"I have no doubt teams will be sniffing, but maybe reaching the last 16 will persuade them all now to stay for a little bit longer."
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