3V resistor? nonono.
What you need is to limit the current going into the LED. You can do this by adding a resistor in series with the LED.
Heres a typical setup :
2V voltage drop on LED (depending on colour/type)
15mA current to pass (depending how bright you want, dont exceed the limit)
Check the datasheet for accurate values.
(5-2) / 0.015 = 220 ohms (the nearest E12 series)
The colour code (RED/RED/BROWN/GOLD) +-5% tolerance.
So put a 220 ohms 1/4 watts resistor in series with the LED...observe the A/K polarity of the LED, the flat side goes on the negative side of the supply.
You can get a 5V LED...probably easier for you