The Buddies were falling to their fifth successive SPL defeat and remain in the bottom two after consistently getting picked apart by the Dons, now in a three-way tie on points for top spot.
They had their fair share of possession and chances, but had only Steven Thompson's late goal to show for their efforts, that goal doing little to ease the disappointment of home fans.
"I must give credit to the players as they gave everything asked of them in the first half, without managing a goal," said Lennon.
"I felt we lost our way in the second half. I understand the fans' frustrations, we must be strong just now.
"The campaign is a marathon, we are hurting at the moment but must keep believing and working hard."