Roshni,
The first thing to note when clicking a sunrise or sunset is that our cameras can't handle if the sun is bright due to lack of dynamic range. A wider dynamic range means ability to hold dark as well as bright areas. Better cameras have higher dynamic range.

So click when the Sun is just rising. A few minutes here and there will make the Sun too hot and flare up. Same thing with Sunset. Just click when the Sun is very close to the horizon. In this case it is but your camera is not able to handle it still.

In the DSLRs what we do is dial a negative compensation so that the Sun appears darker. Not sure about your iphone if there is such a setting. Will investigate and let you know. Just tightly holding a ND filter close or even a dark polythene will also do the same. Quality may slightly suffer if you are using a transparent plastic film.

Horizon shouldn't be at the middle of the frame. Try to position the Sun offcentre in the image. In this case you have done it more to the right. It would also be better if along with that it can be a bit higher or lower in the frame. In case the sky has got a lot of colours, then keep more of the sky and less of water/ground. In this case we can't see much of sky colours. So better to have more water.

You can email me the original unedited image and I will see if the quality is like the way you have posted or not and can give you tips for future posts. Mrudul has already given the link on how to post images.

Cheers,
Sabyasachi