It had been claimed that the Premiership side were lining up a £7million bid for the winger, but Lennon has rebuffed the story - and said there is no way he would consider selling Forrest.
"There is no substance in it," he said. "We are months and months away from the window - he is not for sale.
"There are no grounds for the story. I don't know if people are trying to unsettle players here.
"It is as if everyone wants me to sell a player every month - people talked about van Dijk, Brown, Forster and now James.
"They are not going anywhere.
"It wouldn't surprise me if clubs were looking at him because he is a brilliant player but he has signed a long term contract 18 months ago. He is not for sale.
"We are in a very stable position as a club and that is something which is a rarity in this day and age. The players are happy, vibrant and we have got a lot to look forward to.
"We are on a great run domestically and we're in a hell of a group in the Champions League where we have competed brilliantly in all three games.
And the Hoops boss was delighted with the manner in which his side took all three points from a turgid encounter against Partick at Firhill yesterday afternoon.
"It is a great position to be in and the players are very focused on these games," he said, as Celtic remained firmly at the top of the Premiership table.
"I didn't think we were at our best and a couple of players who looked a little bit off colour - and I understand that."