How do you politely tell your friend that he/she is not invited in your wedding when they ask?

I'd tell them that the wedding is really small (which it is, 120 pax, very small in malay standards) and it's just family and my wedding entourage. My family in itself is big so there'll barely be room to invite my close friends, let alone the "so-so" friends. People should stop obsessing about whether a non invite to a wedding is equivalent to a slight. Sometimes there's simply no room and at the end of the day, it's the bride and groom's day.