Cutting down green tree

Dear Lawyer, I need an advice on cutting of the green tree which is around 15 yrs old. The tree is in front of my house and after that there is a park. The tree is not so big and of neem tree. My neighbour keep on saying me to cut the tree and the cause they are providing used to be different each time. Sometime they said they are not getting sunrays, sometims they said due to tree they are getting leaves waste etc etc. Because of this they fought with us 2 times. Once before around 6 months back they almost cut down a green "shatut" tree pretending that they will cut extra branches but later we found whole tree was finished that still we are waiting it to grow properly. Again the tree was in front of my house not them. I need to know if i can file a complain against them? Or other way to stop them to cut the trees. Sorry I forget to tell I am from Lucknow. And also provide me details of any NGO which is working for this. Please suggest I love trees and I know it is against law to cut green trees.