Diarra has claimed he was "conned" into signing for West Ham.
The Hammers midfielder, who has been loaned out to Rennes for the rest of the season, told France Football: "They were not honest with me. They made me believe I was the priority of the club but it was not true.
"It shows that at my age you can still be conned.
"I wanted (to speak to Sam Allardyce) but he was always at training camps, travelling left and right. At the same time, I had the guarantee of a three-year contract.
"But he came to West Ham with his players, who have followed him for several seasons. The manager was not against my arrival but he was not for it either!
"I was an extra player. It is tough to feel useless. In the end, you have enough of fighting for no reason."
Diarra, 31, played only two hours in five months. "Yes, essentially because I was misled. I could not accept this situation any longer and I went to see the directors. They understood and I thanked them."