[StRaphael]

Try to do something like this:

PHP код:

#include <sscanf2>
#include <zcmd>
new pBlockedID[MAX_PLAYERS];
CMD:blockplayer(playerid, params[])
{
      new id;
      if(sscanf(params, "u", id) return SendClientMessage(playerid, -1, "Syntax: /blockplayer <id/playername>");
      pBlockedID[playerid] = id;
      SendClientMessage(playerid, -1, "You blocked succesfully the player!");
}
public OnPlayerText(playerid, text[])
{
     foreach(new i: Player)
     {
           if(i==pBlockedID[playerid])// checks if the player who send message is blocked
           {
               return 1;
           }
           else SendClientMessage(i, COLOR, text);
     }
     return 0;
} 


hope I helped you!