The Perth side played most of the second half two men short after Chris Millar was ordered off, joining Steven Anderson who was red-carded in the first half.
But despite the numerical advantage and the bulk of the chances, the hosts had only Paul Dummett's goal to show for their efforts as the visitors' overworked defence held out for a share of the points thanks to Murray Davidson's early goal.
Lennon said: "It was frustrating dropping two points. We started well and I was disappointed at losing the early goal, especially as we had talked about the runs made by Murray Davidson which should have been tracked by John McGinn. Apart from that the young man showed great maturity and could have scored two or three goals.
"For the second week running we created so many chances, but we need to be ruthless in front of goal. I thought we made it count when we had one extra man and then two and was delighted with the number of crosses and chances we got in the box.
"Their keeper (Alan Mannus) has made some terrific saves, but while I'm delighted at the chances we are creating we need to take them."
With St Johnstone boss Steve Lomas serving a touchline ban, his assistant Tommy Wright was in charge in the visiting dugout. And he revealed he was very proud of the way his side battled to stay in the game.
"We worked really hard, but nothing surprises me about these players even after we went down to nine men," he said. "We were truly terrific keeping it down to one goal and I am really proud of them."
St Mirren laid siege to their opponents' goal in the final 20 minutes and Mannus had to be at his best to keep them out.
Wright added: "The keeper was terrific and a bit unlucky at the goal after pulling off a great save from the first shot. But he would be the first to thank the players in front of him and Frazer Wright's goal-line clearance and the block by Tam Scobbie typified the spirit."
- Sports & Recreation
- Ice Hockey
- Murray Davidson
- Chris Millar
- Steven Anderson