1998 Honda Civic Whining noise in revving/acceleration

Noises problem
1998 Honda Civic 4 cyl Front Wheel Drive Manual 135k miles

My car makes a whining noise while I either rev or accelerate, it does it at a much lower volume when idling as well. Makes it in neutral as well as in lower gears, I'm not certain that it makes it in 4th or 5th gear, as my car isn't geared to high rev in those gears, I assume it would though. I'm almost certain its not transmission related, as I just had my transmission rebuilt (bearings and all), and I had a clutch replacement about 15k miles ago. I also do not have problems with the battery charging or alternator. I have not had a serpentine belt replacement as of yet, which I'll be doing in the next few days. Could that be the issue? I've also read that it could be the idler pulley, but would that make sense even though it makes the noise at idle? Any help would be much appreciated.