The Gunners are four points adrift of North London rivals Tottenham Hotspur, who currently occupy the last of the the four Champions League qualification places.
The Arsenal manager told Sky Sports News: "I said that after the Chelsea game, we are in a situation where we cannot drop points any more. No matter where we play, we need the three points.
"We lacked efficiency in our finishing, we didn't finish what we created. But we create, and that's positive. We were under pressure to win, and of course we could not afford to drop points.
"Sometimes it's like that. If you look at our games, we score five, seven and suddenly sometimes none, because maybe this team is developing and learning and needs to be a bit more efficient."
Arsenal narrowly beat Sunderland 1-0 yesterday.