brake rotors need to be re-surfaced on lathe machine.
though i'd suggest you to get this machining done (budget solution) but i'd like to mention that re-surfacing 'd take away the hard surface of ur rotor, and u'd ve to get this stuff more often (probably every 2 yrs or so, depending upon the brake pads u opt to choose/servicing etc),
if it comes under warranty then get them replaced.