Nolan Roux's stoppage-time winner saw Lille to the win, closing to within a point of league leaders Paris Saint-Germain.
But Seydoux said Lille were focusing on themselves rather than worrying about their nearest rivals, with PSG facing Evian TG on Wednesday.
"At the moment we just look at the number of points we have and we look at the number of points that separates us from other teams," he said.
"Ahead of us there is PSG, but there are also teams behind us. Week 16 is not over yet."
Roux headed in Florent Balmont's cross from the right in the first minute of additional time to give Lille a dramatic win.
Seydoux was delighted Lille came out on top in the end, but praised Marseille for staying compact throughout the clash.
"Nolan Roux was amazing," he said.
"In this kind of game, everything is possible. Marseille was very well organised. The game was very open and kept us in suspense.
"The suspense lasted until the end. When you are watching a movie, it is nice to have good news before the end of the film – a kind of happy ending. It was the case for us, not for Marseille."
