The Frenchman was tipped to star for the English champions this year after an impressive Euro 2012, but has failed to make any major impact at City so far this campaign.
Manager Roberto Mancini recently joked that he would like to punch the Frenchman over his form after a good display in the 4-0 win over Newcastle United earlier this month, and the 25-year-old agrees with his boss that he should be playing better.
"I am aware that I have not had a good season," Nasri told The Mirror.
"There are many reasons, but when Mancini said that I'm training at 50%, this is not true.
"I felt comfortable against Newcastle. It's been a while since I felt good."
Nasri also dismissed rumours that he could move to Paris Saint-Germain or Monaco this summer.