The 21-year-old arrived at the Emirates for a £27m fee in the summer of 2019 but has only made eight appearances for the Under-23 team so far.
However, Jorge Sampaoli selected Saliba 51 times for Marseille in all tournaments last season, with the centre-back helping Les Olympiens qualify for the Champions League with a second-placed Ligue 1 finish.
Marseille have made no secret of their desire to strike a permanent deal for Saliba, but Arteta recently stated that the France international "has to come back" to the English capital.
Speaking to RMC Sport, the Gunners boss said: "We made the right decision. He has to come back. William wanted to be a regular starter as you know but now we want him back at Arsenal.
"He has the experience and the environment necessary to be competitive with us. If he had stayed with us this year, with a match of Premier League a week, with Ben White and Gabriel, he wouldn't have had half the playing time he had with Marseille, that's for sure.
"For his growth and what he can do next season that wouldn't have been good. William wasn't with us because he wouldn't have had the playing time to gain experience. That's it, there's nothing else."
Now, transfer expert Fabrizio Romano reports that Saliba could also be in line for a new contract at the Emirates, as his current terms are due to expire in the summer of 2024.
Romano adds that Arteta and technical director Edu consider Saliba to be a vital part of the club's future, and the former is planning to integrate the Frenchman into first-team training during the pre-season period.
Nevertheless, Marseille president Pablo Longoria is not giving up hope of signing Saliba permanently, telling RMC Sport: "We had a lot of conversations analysing William Saliba's season, especially in the last few days. He's coming off an extraordinary season, with one of the highest number of matches played in Europe.
"He also joined the France team, which is incredible at his age. We discussed a lot internally about what we can do, to find out what the possibilities are.
"We respect his club, we have to thank Arsenal. It's a friendly club that helped us a lot during the last transfer window. We have very good relations. We have to talk to each other, see if there is the possibility of reaching an agreement between the clubs, there is the player's will, the club's will, but above all, we must respect Arsenal."
Saliba has also confirmed that he would be keen to experience Champions League football with Marseille after winning the Ligue 1 Young Player of the Year and making the Team of the Year for the 2021-22 season.
Matteo Guendouzi and Sead Kolasinac have both left Arsenal for Marseille over the past 12 months, and Arsenal supposedly consider Barcelona's Samuel Umtiti as a possible replacement for Saliba should the France international aim to force through a permanent move to the Orange Velodrome.
Saliba's strong showings for Marseille helped him break into the France setup earlier this year, and he has been included in Didier Deschamps's squad for June's Nations League fixtures. body check tags ::