You can't prevent international buyers from purchasing from you, per eBay's rules. You can only prevent them from making you ship international. What you're doing (cancelling those orders) is a quick trip to the end of your selling days on eBay.
Reshippers, usually known as freight forwarders, are perfectly legit, and while scammers can use them too, nothing about those orders makes them likely to be a scam. Also, you have some additional protection against INR claims if you can prove to eBay that it was reshipped from where you sent it, per policy.
Lastly, you can just enroll in the eIS program and forget the whole business of not shipping internationally, because then eBay guarantees the transaction and you have much lower risk that any domestic sale.
Basically, change your thinking and your practices or you'll be in a heap of trouble with eBay at some point.
