The defending French champions suffered their first Ligue 1 defeat of the season as they went down 2-0 at Parc des Sports.
"We managed to create some clear-cut chances in the first half," he told reporters. "In the second, apart from the one for Javier [Pastore], we didn't create a lot.
"We can have regrets, because in the first half, we could have and should have opened the scoring, which would have allowed us to have a different final score.
"But we were too mediocre in the second half to hope for more. ETG were very compact in the first half. They would have had a problem if we'd opened the scoring. At 0-0, they were able to believe they had a chance. Bravo to them."
PSG are currently a point clear at the top of the league table.