Mr Groser wanted to clarify that the agreement would be open to debate once the deal was agreed upon.
"It's something we will have a big debate on at the time, but this is not the right time yet.
"I'm extremely confident that the government will be able to convey to New Zealanders that there is no cause for concern here whatsoever.
"Let's have the debate when we're looking at something that's real, not some version of reality."
Mr Groser said the sticking points were around agriculture.
"The really sensitive issue is agriculture market access, and once again New Zealand, because of the nature of our competitive economy and we are a little super power in world agriculture, we are the centre of the maelstrom around that."
He said the politics of the agreement were "fraught" in many countries but not in New Zealand.
"It's pretty obvious to us where New Zealand's interests lie."
Edward Miller, one of the organisers behind the protests, said thousands of people had expressed their intention to be a part of the protests yesterday.
"There has been a massive response to the call for Kiwis to fight back against a deal that puts the interests of big corporations ahead of ordinary people."
President of the New Zealand Council of Trade Unions Helen Kelly said: "We are urging people to support this day of action because the TPPA contains threats to our health system, our public services, our ability to use government purchasing to develop our economy and improve our environment and working conditions, and our right to make changes to our laws and regulations in the interests of most New Zealanders."
Events were held in Auckland, Hamilton, Tauranga, Raglan, Rotorua, Gisborne, Napier, Wanganui, New Plymouth, Palmerston North, Levin, Wellington, Nelson, Christchurch, Timaru, Dunedin and Invercargill.
