The paper presents a passive islanding detection scheme for both synchronous and inverter based distributed generations interfaced to microgrid using Decision Tree. The scheme involves extraction of different features at target DG location and builds the Decision Tree for intelligent anti-islanding protection. Extensive simulations are carried out including wide variations in system loading and power mismatch during islanding, and a comprehensive Decision Tree is built for effective islanding detection for both synchronous and inverter based distributed generations in microgrid. The performance of the proposed data-mining based anti-islanding scheme is compared with existing Rate of Change of Frequency and Rate of change of Voltage relay and, provides improved performance at lower end power mismatch.