The Arsenal forward limped off as the Gunners beat Crystal Palace in the Premier League at the weekend and Arteta fears that he could be missing for a long time with a torn hamstring.
The coach said: "It’s not looking good. He’s going to be out for many weeks.
"It’s a huge blow but it’s going to be a big exercise for us to overcome another challenge. I’m very optimistic he’ll be back before the end of the season.
"[It’s] another part of the development of a player. At some stage at this level you’re going to get injured. Unfortunately, badly. It could have been much worse. It could have been something else that can take you out for a year.
"It is what it is. He’s injured, we cannot change it. We’re going to use this time now to help him."
Arteta confirmed that Saka was devastated by the news of his injury but is hopeful that the star can still contribute to the dressing room despite his absence.
The Spanish manager said: "He was gutted. You can tell that he has not been injured because he was really, really emotional and really down. And we need to lift him up. It is a big part of his job. He will be fine but he is going to need a few days.
"He will immediately realise that he is so important in that dressing room. His energy level, his body language, and how he communicates with the rest of the team has to be really good because it is the only way at the moment he can help, so he better do that well."