The Blues have hit a fresh form slump and were hammered by the Seagulls on Friday night.
Maresca said: "This result the frustration is about everything. For sure, we feel really sorry for the fans that come here and the moment that we are in the position we are in, we need to do much better than what we have done tonight.
"I think in terms of controlling the game or keeping the ball we did that. But I said before the game when you don't have a nine who can be a threat we need to find different solutions. It is not only about chances.
"There are many things we have to do better. We still have many games to go and we are still in a good position. We need to do our best and try to finish in the best way.
"We are in a moment when we feel we can concede easily and struggle to score. I think before the goal they didn't have some chances. There are many things we can do better.
"It is not only mentally. When you play these games in the moment we are, where you can make the gap bigger to the ones behind us and you perform like we did tonight, there are many things that we need to do better.
"I feel sorry for the fans. It is not the right performance that we can offer, especially at this moment in the season. We need to stick together.
"I feel pressure always. We are tonight the performance was the worst since I arrived so it is not the right moment but we are still in fourth and in the race to finish in Europe."