Hello vaib.s,
The typical way to control a brushed DC motor such as this is using an H-bridge motor controller. This allows the motor speed and direction to be controlled.
As a starting point for your MG16B-300-AA-00 motor, may I recommend the MDD3A. You may be interested in this recent article describing how to use the controller.
Please describe your software and we may be able to offer a better solution. For example, if you are using PC based control, you may need to include a microcontroller to feed the appropriate PWM signals to the motor driver.
Best Wishes,
APDahlen