The Grecians led two-nil at half-time thanks to goals by Danny Coles and Scot Bennett, but Jon Nurse pulled one back before Andy Iro bundled a last-gasp equaliser eight minutes into stoppage time.
"It sums up where we are at the moment," Tisdale said. "It was a tentative last 10 minutes. We ended up conceding very last gasp and it is terribly disappointing.
"I'm sure the referee had good reason to play eight minutes. I mean, there were injuries to Edgar Davids and Liam Sercombe, but I often watch replays of home games and we don't seem to get it. It seemed very generous, but there's nothing I can do to change it. I still expect us to defend well and see it out.
"We were terrific in the first half and we could easily have scored four or five. We had energy and the players did everything I asked them to do. Two-nil probably did a certain disservice.
"I could see we were getting deeper and didn't put pressure on the ball. Everyone could see that, but it's hard to affect that. Players have to be brave and get closer to the ball and be strong, but it's not always easy to do.
"We didn't do a lot wrong in that last 10 minutes, but the game changed and we probably had as many chances as them in the second half."