Torres has been consistently blasted by sections of the media since making the £50m move to Stamford Bridge, and has just nine Premier League goals in 51 Chelsea appearances.
Arteta has admitted that he has been upset by the way Torres has been treated and does not envy the pressure placed on strikers to deliver.
The Spaniard told the club's official website: "I don't like the way he has been treated because I have known him since we were 16, 17 and I really appreciate him.
"He is a friend of mine. Obviously, football is like that, it doesn't matter what you have done in the past, it is only what you have done in the last few weeks.
"He has been criticised but mentally he is a really strong guy even if someone doubts him. For a striker, sometimes it is not fair, it can be very tough."
Arsenal and Chelsea both defend their unbeaten records when they play in tomorrow afternoon's London derby.