Your microcontroller pins can not supply enough current.
If you are lucky, you have not damaged your chip. You will need at a bare minimum a transistor circuit capable of handling your motor’s current demand. For example, a smallish dc motor will require say a minimum of 50mA. Your microcontroller pins can, at best, offer 40mA.
If you could/would, please put the LED back in the circuit on the same pin and let us know if it still blinks.
It contains a set-up tutorial to run a motor from an Arduino for beginners. I think there’s one problem in the schematic though - you don’t need the resistor that goes to Pin 9.
... I'm just wondering what it is in the datasheet that says it is appropriate to boost the current to an acceptable level (is it the 600mA Collector Current)?