current in diode circuit, will depends upon the current limiting resistor value we put in series with diode.
let me explain you, what happens if no resistor, when supply voltage is greater than 0.7V, say 3.3 V, then internal resistance of diode which is very low in milliohms comes in to picture, and a current of value 3.3 (supply)-0.7(diode drop for silicon)/ x mohm = many amperes flows in circuit and your diode burns.
So to avoid this we put series resistor in place and it is called current limiting resistor (for its function).
consider an LED circuit.
normally a 15-20mA is a good current to pass in your LED circuit. So, resistor calculation is as followed:
drop across resistor: 3.3 - 1.5 (for LED) = 1.8
current = 20mA
value= 1.8 / 0.02 = 90 ohm