The Russia forward was impressed with Arsene Wenger's deadline-day signings but admitted that the departed midfield duo are irreplaceable.
"At the moment, losing Fabregas and Nasri is a catastophe," Arshavin told Sport-Express.
"He smiled and replied, 'Yes, the only player who could properly replace Cesc is probably Xavi'.
"I'm very glad that I was able to play in the same team as Fabregas - he is a truly class footballer.
"When people say no-one is irreplaceable I don't agree. With (Mikel) Arteta or whoever replaces those who have left, we will play different football, not as we played with Cesc and Samir."