"Don't come to me if [National] win, and they go back on their word."
An ageing population that will live longer has seen some experts call for the age of entitlement to go up.
John Key had said he would quit as prime minister before raising the retirement age of 65. In December, new Prime Minister Bill English said he would not renew that pledge.
Labour in 2014 campaigned on raising the eligibility age, but now leader Andrew Little does not support an increase.
Act Party leader Seymour - who said in a Herald interview this week that Peters was a "charismatic crook" - has called for the age to be raised to 67, matching other countries including Australia.
Today, Peters hit back, to laughter from the audience.
"If you have observed - the number of people saying we can't afford Super, all sorts of economists, all sorts of political parties. Why, there's a ventriloquist dummy in Epsom who says that we can't afford you.
"This is a guy, who alongside [United Future leader] Peter Dunne, their two parties couldn't even get 1 per cent at the last election."
Peters said it was wrong to label NZ Super unaffordable, given immigrants could access the scheme after 10 years.