The Gunners won 2-1 at home over rivals Manchester United on Saturday.
“It could be tighter than everybody expected it to be because the teams in the second part of the league have improved,” he said.
“To go away and win at Stoke, at Blackburn, at Bolton, at Wigan, it’s difficult, more difficult maybe than 10 years ago.
“And to deal with the Champions League and all these games is very difficult.”
He added: “I didn’t imagine the consequences of a defeat. I felt beforehand that it was important not to think about that, just think you want to win.
“Part of the preparation was to go into the game with a winning attitude – that is what we tried to build up.
“If you open the press or listen to the media, you always have the feeling that the world will stop if you lose the game.
“But, in reality, it goes on the next morning. When you are under a lot of fire from the press, it’s not easy and I believe this team has a lot of character.
“They have shown that and kept playing the way we want to play.
“In our job, we can talk, talk, talk but, at the end of the day, it’s what you produce on the football pitch and against United the answer was right.
“When you don’t win you get criticised and you have to take that and deal with that and show that you can take it.”