How do I prevent people from joining my Minigames Server?
Solution 1:
Unfortunately, the PS3 edition does not support any "server" management. The only way to play is online over the PSN, or over LAN.
Because of this, there is no "whitelist" which is how you would normally manage this.
So aside from reporting the players, you would only be able to do this via a VPN, or locally over a LAN network.
Solution 2:
What you could do is set their spawn point in the void, or make a 2-tick comparator command block clock that kills them automatically that sets off every time they join using the /testfor command as a trigger.