You would need the LM350, that is the open with a 3A limit.
They are linear regulators that can be used as current sources, although you could also see them as a current limiter or a variable resistance which values increases as required to ensure that its does not feed too much current.
To use it, you only need to put a resistance between pins 1 and 2 so that Imax = 1.25V/R.
At the end (either with this, with a resistor or with a any other regulator), what you are going to do is to reduce the tension at which the motor is going to operate. There is a minimum voltage at which the motor start rotating. If you low it too much, it will not start.
Check it before.