BEIJING, June 15 (Reuters) - China"s industry ministry on Tuesday said that it had told e-commerce giants Alibaba (9988.HK), JD.com and Pinduoduo (PDD.O) to regulate their use of promotional phone messaging to users ahead of the annual June 18 shopping festival. The directive, delivered during what the ministry said was a meeting on June 11, is the latest move in an ongoing regulatory clampdown on China"s booming "platform economy".