Other details about this motor are more important than its dimensions. How much voltage and current does it take? That will determine how you can control it from Arduino.Also, knowing what kind of motor is it? Is it actually a rotating motor with an offset weight?Or is it some sort of "buzzer" kind of device? Some of the "buzzer" devices have built-in driversand/or they achieve maximum movement by being resonant at some particular frequency. If your gadget has a built-in driver or it is resonant, then you cannot control the frequency.But without knowing more about your "Shaftless Vibration Motor" we would be shooting in the dark.
Yes it appears that you can probably control it with Arduino PWM and a transistor (because of the current). I wouldn't expect a wide range of frequencies.