Is it safe to run these motors with raspberry Pi directly?
What ever motor you are using, don't connect it directly to the Raspberry Pi. It is not safe to use them directly with the board. Use a motordriver to connect them. i am saying a motordriver module because, it will be easy to just connect the input and output wires. it is upto you in using a Motordriver module or making your own H bridge circuit. Even simpler boards like Arduino require motor drivers for connecting the motors. This is mainly because the motors draw more current than the board can provide. I am no expert in Raspberry Pi, but using a motor driver with the board will be preferred.