Les Verts twice took the lead against the relegation candidates at Stade de l'Aube but had to settle for a 2-2 draw.
"We clearly missed a chance to take all three points tonight," he told reporters. "We were fortunate enough to lead twice in this match, but we could neither hang onto the result nor kill the match off.
"Our defensive work was sub-par, which is the mark of a side that is still a few steps away from the highest level. It's great to want to score goals, to play good football, but when you're in front, the most important thing is to secure your lead.
"It's really infuriating. We didn't need to do better; we needed to do more."
Saint-Etienne are currently fourth in the league table with 50 points from 30 matches.