Diba is a forward who was made his debut in professional football during the 2002–03 season, being part of the NAC Breda squad. He spent five seasons with NAC in the Dutch Eredivisie.
In the winter of 2011, after sustaining a leg injury, Diba had to be treated in London, subsequently missing much of the league matches of his then-new club, Lekhwiya. As a result, Diba was cut from the squad. While numerous news outlets had reported Diba's departure, he himself had not received any official confirmation of being released by the club officials, and was first informed after receiving calls from his agent and friends. Before Diba's trip to London, Lekhwiya coach Djamel Belmadi had claimed Diba was one of the most prominent professionals in the team. This came as a surprise to Diba, as he was just 2–3 weeks from being released from the hospital.