3V DC Motor - 9V Battery?
You've probably got something similar to one of these: -



And if you have these are probably not going to be able to supply the start current needed to get you motor moving. They have a typical DC resistance between 2 ohms and 4 ohms and these are pretty good types. Others may have an internal resistance of up to 10 ohms and, of course you may be using a partially discharged battery.

Either go for a couple of AA batteries in series (having a total series internal resistance of about 0.3 ohms) or use a buck regulator to drop the voltage (efficiently) to 3V.