Russell Penn scored the only goal of the game after just five minutes with a low drive from the edge of the penalty area - leaving the Grecians four points adrift of the top seven heading into the final weekend.
And Tisdale was left to reflect on injuries to key players at a crucial time of the campaign.
"It's disappointing and there are plenty of reasons why that is the case. We have been left wanting in one or two areas of our game," he said.
"I am really pleased with the way the players and the squad have committed to the season and I thought it was a fantastic effort again here from a group that has been depleted by injury of half-a-dozen definite starters.
"We had young players coming into the side and I thought they played really well, especially in the first half, and it summed up the season really. We have lost to Cheltenham twice, have played extremely well on both occasions, but haven't scored.
"We had plenty of shots and snatched at a few. Maybe we could have done better there, but I thought the performance in the first half was one of our best of the season.
"Bringing the youngsters into the side is a sign of things to come and we will certainly be seeing more of them next season."