The Hoops boss was handed an immediate three-match touchline ban on Thursday for confronting referee Euan Norris after his club's William Hill Scottish Cup semi-final defeat by Hearts last month.
He said: "All I will say is that I got a fair hearing, I think the punishment is pretty fair as well."
Lennon, who had just served a two-match touchline ban for criticising referee Willie Collum following Celtic's Scottish Communities League Cup final defeat by Kilmarnock at Hampden in March, received a six-match ban in total, but half of the punishment was suspended until the end of next season.
He added: "I expected to be punished. I have apologised to the referee in correspondence and he has responded and he is grateful of that and we move on. The judicial panel don't want to be punishing people, but when you cross the line I expected to be punished and I have been and I am going to learn from this.
"I will have a suspension hanging over my head and that is a warning for me. If I step out of line again I could get three matches plus and I don't want that."
Stokes, one of seven changes to Lennon's side against St Johnstone, struck from close range in the 29th minute after strike partner Mo Bangura had caused some confusion in the visitors' defence following a corner.
Lennon said: "I was very pleased. It was another clean sheet, 24, that's a record. It takes us to 90 points with two games to go and that's tremendous consistency after 92 last season."
When St Johnstone visited Celtic Park last month, boss Steve Lomas complained about three key decisions going against his side in the 2-0 defeat. This time he complained about two.
He said: "I was disappointed with the manner of the goal. I didn't think it was a corner at the start and we were told that it was offside. I could be proved wrong but whenever the cross came in Bangura helps it on and the guy was offside."