[RajatPawar]

Basically, just add an IF statement above the code. If I want to allow only players with a var which has a value more than 3, I would:

pawn Код:

CMD:blabla( playerid, params[] )
{
   .. ... . .
   if( player_VAR[ playerid ][ some_level ] < 3 ) // he doesn't meet the requirements
      return SendClientMessage(playerid, -1, "You do not have enough 'some_level' level.");
   else
   {
            the code
    }
    return 1;
}

EDIT: late