There's a stray cat, who gave birth to kittens around 2-3 weeks ago inside a cupboard in my balcony(1st floor). Can i pet her or her kittens?? I tried providing her with milk, and petted her with my hands once. Most of the times the cat is away and the kittens feel a little feared when i touch them...

You can try to pet her if she will let you. She doesn't need milk, she needs water. The kittens should start to be handled more to socialize them, and I would do it slowly and carefully. Interact with them a little bit every day, and increase the time and contact you have with them. If their eyes are open and they are moving around, you can give them toys to play with, and you can interact with them using the toys. When they are around four weeks of age, they can start getting a kitten mush to help them wean. To help them wean and to get used to dry food, I would soak a high quality kitten formulated dry food in warm water until soft. Then mix that with kitten formula such as KMR to make a mush the consistency of oatmeal. Over the next two weeks, gradually increase the amount of dry kitten food and decrease the amount of water and KMR you use until they are eating the dry kitten food only.

Oh they are so cute! From the picture, it looks like they may be old enough to be on a kitten food, and I will give you a method to get them onto it. If you don't want to keep them, I recommend taking them into the SPCA in the morning. The SPCA can get them the medical treatment they need and can find them a home. To help them get used to dry food, I would soak a high quality kitten formulated dry food in warm water until soft. Then mix that with kitten formula such as KMR to make a mush the consistency of oatmeal. Over the next two weeks, gradually increase the amount of dry kitten food and decrease the amount of water and KMR you use until they are eating the dry kitten food only.