In the old days, before dedicated drivers with current limit, simple series resistors were used with stepper motors. They produce quite some heat, but can be Ok for a not so demanding application. Using a series resistor can be still more effective than reducing the voltage with a linear regulator, as the current can still rise faster which thus allows a higher speed.
If the motor does not need to run fast or deliver a high moment there is no need to use the full rated current. Something like 70% of the rated current already reduces the power loss in the motor to about half, so keeps the motor significant cooler.