Diarra, who represented France at Euro 2012, joined West Ham in the summer but has made only one Premier League start after suffering a loss of form and struggling with injuries.
Now the 31-year-old says he is attracting interest and feels the time is right to quit the club.
"I want to leave," he told L'Equipe. "I've tried to stay positive right up to now. I want a real challenge, and I won't get it at West Ham.
"With the current coach in charge, it's impossible. No one's told me directly, but I'm not stupid. I'm not part of his plans. I have to leave.
"Some clubs have already contacted West Ham. I'm not afraid to change countries. It'll still be better than here. The objective is to get back playing. Last year, I played some 60 games. At West Ham, I've wasted my time."
The France international claims he was sold false promises when he joined the club and that he has a non-existent relationship with manager Allardyce.
"He is obviously clear, without telling me, that he is not happy with the situation, which is understandable," the West Ham boss said. "You get this all the time as a manager when you bring a player of his experience and calibre over from France.
"It hasn't quite worked out and he feels a little disgruntled in terms of playing more, this or that.
"It is a fact of life, whereas I look at the situation and play what I consider the best team and because of Alou's long-standing injury he has found it hard to adjust to what is needed in the Premier League.
"If he is unhappy, he just has to tell me what he wants to do and we'll see how we go from there. At the moment, yes, he contributed well but his frustrations he obviously wants to play more.
"We'll have that discussions and we'll make a decision after that on the future of Alou."