The Premier League giants were beaten 2-1 by their rivals Fulham in the west London derby on Boxing Day.
The result puts a huge dent in their hopes of winning the title, with Liverpool beating Leicester on the same day.
“Yes, there is some frustration, especially for the way we conceded the goal at the end,” said Maresca post-game.
“It’s a bad feeling, also because I’ve said many times, when you can’t win it’s important you don’t lose.
“I think the first 15 or 20 minutes of the second half was the part I didn’t like, because we conceded too many transitions and we knew they are a team building from transitions, with (Alex) Iwobi, Adama (Traore), (Antonee) Robinson and (Raul) Jimenez.
“In the first half I felt we controlled that very good, we scored and created chances, then in the second half I think we gave them too much energy in the first 15 or 20 minutes. Even when they’d equalised we had some good chances, with Marc (Cucurella) and Jadon (Sancho), but it was a shame.”