Galtier said that he was happy with how his team played in the first half, but raised questions over their second-half display.
"We have taken a point and, while we had to struggle to do so against a very good Rennes team, we never doubted ourselves," Ligue1.com quotes Galtier as saying.
"In the first half, I was satisfied with the way we played. In the second half, we suffered a lot, but we showed character and managed to equalise at a good time.
"From a pessimistic viewpoint, I am disappointed that we conceded two goals. From an optimistic viewpoint, I am delighted that we scored twice. We still have a six-point advantage over Rennes, which is a good thing."
Saint-Etienne are fourth in the table, one point behind Marseille.