He said those at risk were not casino customers but "mums in South Auckland" who were shopping in communities where there were pokie machines at clubs and pubs.
Morrison said SkyCity was "destination gambling" not "convenience gambling".
"The reality is public transport in Auckland isn't that great. You don't just arrive at SkyCity. You make a deliberate decision to go to SkyCity.
"The incidence of harm cited from Lotto is greater than that from pokie machines in casinos. Getting those facts across is difficult."
Morrison said the casino also wanted to increase the number of table games - such as blackjack or poker - beyond the 110 it currently had. He would not say if that was part of negotiations.
"We're not just on about growing our gaming machines.
"We would like to grow our table games product and expand our operations to meet the growth of Auckland."
He said a decision on the convention centre "one way or the other" was likely to be made within six weeks.
He said a key component was the amount of money SkyCity was going to be able to make out of the deal.
"As a public company, we need to make sure we can earn an economic rate of return for our shareholders, 95 per cent of whom are New Zealanders."
He said the casino was too small for the number of people who wanted to use it.
"If you come here on a Wednesday night or a Friday night, the property is full.
"It is uncomfortable. You can't enjoy it anymore. We clearly want to expand our business. There is clearly demand for it.
"There will continue to be demand for it. We think it is a very good business and a business worthy of promoting and expanding."
Green Party co-leader Metiria Turei said there was evidence showing pokies caused "significant harm". "New Zealanders are going to suffer the consequence of SkyCity buying a change in the law."
Problem Gambling Foundation chief executive Graeme Ramsey said the negotiations between SkyCity and the Government would be done for the benefit of the casino. "Sky City aggressively pursue opportunities they see to increase their gambling revenue."