Serbian defender Stefan Mitrovic headed Strasbourg into a 73rd-minute lead before Dario Benedetto rescued a point for Marseille four minutes from time.
"It was not easy against a well-organised team," said Marseille coach Jorge Sampaoli.
"Fortunately we were able to equalise but we didn't have the capacity to do better.
"Our opponents neutralised us, we couldn't put our game plan in place and so it was frustrating."