The Genius Media Nigeria reports that the Spaniard also gave reasons for his decision to hook Nuno Tavares after half an hour.
The Gunners suffered a 1-0 defeat to Forest in the third round of the FA Cup as Lewis Grabban came off the bench to give the home side the win and take them to the next round of the competition.
“They won, they scored a goal and we didn’t,” Arteta told reporters after the game.
“We were not good enough and we have to apologize for it.
“I don’t want to use excuses, I expect the team I put out to do better and when you don’t in the cup, you are out.
“Today showed we were not capable of winning against Forest away from home and didn’t put in the level to win the game. It’s a collective issue and today we have not done it.”
On why he substituted Tavares so early, in the end, he added, “I just did it to try to improve the performance of the team.”