Nasri also revealed their Carling Cup final defeat hurt the players psychologically.
The France international insisted it was the right time for him to leave, telling l'Equipe: "Yes, it was [the right time to leave], there are sure signs.
"The departure of Cesc to Barcelona is one of them. The defeat against Birmingham in the League Cup final was very harmful for the minds.
"Arsenal doesn't have the same funds. They can't make the same coups as before in the transfer market. They are rather forced to sell their best players and bet on young ones."
"In this last one there was a clause that Arsenal officials didn't really accept.
"Then, it lasted. When they came back to offer me again in June, I made my decision. In my mind I wanted to leave, above all after the very difficult end to last season and I also already had nice contacts.
"At first Arsene Wenger wanted to keep me. Then, both clubs needed time to agree a transfer fee.
"My agents worked well. With the lawyers they wanted everything to be in order. When the transfer is big, you have to be patient. I am also happy Arsenal could get a nice fee. I prefer to leave that way than being a free agent. I did the same at Marseille. But that €28million fee doesn't put me under any pressure."