safe way to attach coin vibration motor to arduino

As the motor is only to generate vibrations (no shaft) then there is probably no need to run it forward and backward. A simple transistor will do the job tip120 transistor: controlling dc motors and lamps from the arduino | Connect the Dots The motor is only 2.5-3.8 volts so you will need a suitable way to power it. The UNO's 3v3 output is only rated to 50mA so is not suitable