The 34-year-old, who has also played for Fulham, is currently a free agent after his contract with the Hammers expired at the end of the season.
"I am trying to convince the managerial staff of Birmingham. If I can get a deal here, I would like it. Birmingham is a big club, at my age it is a great challenge. I hope to impress them and get a contract," he told Sky Sports News.
Diop made 63 appearances for Senegal.