Will a higher voltage to get the desired current hurt RGB LEDs?
This isn't any different for RGB LEDs than for any other set of 3 LEDs:
You can't put them in parallel with a single series resistor. Every color LED needs its own resistor.

but my 4m power cable is 3 ohm an this is the problem

Yes. This means you need a better cable. I don't know which cable you're using, but even a single 0.180 mm diameter copper wire strand (AWG 33, that is literally as thin as the average human hair) has lower resistance than that... My guess is you have a measurement artifact in there, and there's no problem at all.