Just looked at your exif - you're on ISO 1250, which you don't normally need unless you're shooting at night handheld or indoor sports. Take that down, decrease your shutter speed and it'll be less grainy while still correctly exposed :)
This is really pretty though, the soft colours and shallow depth of field give it a lovely delicate feel
I agree with Annie and Alli both! Yes, the lowest ISO will give you the best clarity. I generally try to shoot at 100, but that will limit either your shutter speed or aperture, so it's a trade off. In general the brighter the light, the more you can afford to dial down the ISO. That said, sometimes grain (or noise as it's called in the digital world) can be a desirable feature. With a shallow depth shot like this, I like it a bit grainy myself. Nice photo!
This is really pretty though, the soft colours and shallow depth of field give it a lovely delicate feel