"This is a meaningless formula. Rostered hours are a long way from hours worked, which is the formula we have used at Restaurant Brands," he said.
"Rostered hours are completely under the control of the company. They can go up and down at their discretion ... Workers will have no way of knowing whether the roster is fair and equitable.
"We need a guarantee of hours based on the hours a worker usually works, not what they are rostered. That way, it also allows guaranteed hours to build up over time."
Mr Treen said there was no commitment to regular fixed shifts in the future, which was a very important aspect of the agreement with Restaurant Brands.
"Workers want to be able to plan their lives and with shifts that change week to week it simply isn't possible.
"We have not accepted this so-called offer from McDonald's. We remain in dispute with all three companies."
Mr Treen said bargaining continued, and he asked the public to "keep up the pressure on these three companies until we have genuine offers to end zero hours".
McDonald's this afternoon said it was not surprised by the union's response.
"McDonald's is committed to reaching an agreement with Unite on security of hours, and today we have moved to address this and do away with what have been labelled 'zero hours contracts'.
"Unite's public statements today are a distraction to our new position around security of hours; we are not surprised they have found fault with our offer and still intend to strike on Wednesday, given they already had plans in place to do so."
McDonald's NZ earlier said it had reviewed the structure of contracts and presented an offer of 80 per cent security offer in its latest round of collective bargaining.
The company said it had been in discussions on the employment contracts for several months, and understood that security of hours was important to people.
Under the offer presented, all workers would receive 80 per cent security of hours up to a 40-hour cap, based on the average of the previous 12 weeks, McDonald's said.
"We would note that the above structure has previously been common practice when it comes to scheduling in our restaurants, but it will now be formally written into employment agreements," McDonald's said in a statement.
"We will continue to bargain in good faith and hope to reach a mutually acceptable agreement soon."
Last week Restaurant Brands, which owns KFC, Pizza Hut, Carl's Jr and Starbucks, said it would do away with zero hours contracts.
The Unite Union at the time called the move "a gigantic step forward for workers in the fast food industry".