But Joe Carolan of the union said the demand was reasonable and would amount to no more than $21m for the weekend pay.
Protesters were on Hobson St opposite the $703m NZICC, scheduled to be finished later next year.
SkyCity is flush with cash, having sold its Darwin property for $188m, its Auckland underground carparks for $220m and a Federal St carpark near its headquarters, netting around $450m.
Asked in August what plans the business had, chief executive Graeme Stephens said: "We have been doing a share buyback. We don't need all that money today and we are lowly geared. We have not made any big commitments to new projects outside the convention centre, so we're under-geared but we are also taking note of the environment we're in and it looks like it might be a bit more challenging. We're being conservative but keeping monitoring that position."