Limiting Power to Dc Motors

I have 2 dc motors that i will control using an arduino using pwm, my input voltage is 9.6 volts from a battery, but i will use a 5v voltage regulator to power the arduino, the motors are 3v motors. How would i limit the voltage to them using resistors, i have two motors here are their specs
Typical operating voltage:  3 V
Free-run motor shaft speed @ 3V:  12300 rpm
Free-run current @ 3V:  150 mA
Stall current @ 3V:  2100 mA
Motor shaft stall torque @ 3V:  0.5 oz·in