[Kush]

I've made it using zcmd and sscanf:

pawn Код:

CMD:pm(playerid, params[])
{
        new PID, pName[MAX_PLAYER_NAME];
        if(sscanf(params, "us[128]", PID, params)) return SendClientMessage(playerid, COLOR_GREY, "USAGE: /pm [playerid] [message]");
        if(!IsPlayerConnected(PID)) return SendClientMessage(playerid, COLOR_GREY, "Player is not connected!");
        new Str[128];
        GetPlayerName(PID, pName, sizeof(pName));
        format(Str, sizeof(Str), "Admin says: %s", Sender, params);
        SendClientMessage(PID, COLOR_WHITE, Str);
    }
    else
    {
        SendClientMessage(playerid, COLOR_GREY, "You are not authorized to use that command!");
    }
    return 1;
}