Hooper was a target for Norwich City in January and a host of English clubs, including QPR, are reported to be pursuing the striker this summer but Lennon is unconcerned.
"We knocked back £6milion for him in January so we won't be bullied by big-money offers for any of the players," Lennon told the Daily Record.
"We have a team full of prized assets here. We're comfortable with our valuations and if they are not met we are not in any desperate need to sell them.
"But Gary has been brilliant. I haven't seen a change in attitude at all from Gary and I haven't had to speak to him."
Lennon appears more reconciled to the prospect of Victor Wanyama moving on but anticipates he would receive funds in order to replace the star midfielder.
"I'm sure I'll get some of the money if Victor goes," added Lennon.
"I don't know how much I'll need but I wouldn't imagine I would need to spend the whole £10-12million."