Tree identification

This appears to be a flower of a tree in the Syzygium genus.

Because there are many species (1200+) -- many which are intentionally planted as ornamentals outside of their native range or have the propensity to become invasive -- I cannot confidently provide a more specific species given the garden location in which you found your specimen (and lack of further details).

I include, as an example, an image from the University of Connecticut of Syzygium jambos, which is not native to India, but is known to grow in nearby regions.

Notice the similar floral architecture to your specimen: dominant androecium (literally hundreds of stamens), whitish color, 4-lobed calyx, prominent hypanthium, etc. Multiple flowers also similarly cluster at the end of branches as in your photo.

• Read more about S. jambos's floral description here.

Sometimes-similar Eugenia cannot be totally ruled out based on your limited photos/details, of which 25 species occur in India. However, Syzygium still seems much more likely.

Overall, I can update my answer with more details once you've updated your post.