Finance Minister Conor Murphy has claimed the financial offer from the UK Government for Northern Ireland "falls way short".
The Sinn Féin minister was speaking after the parties met with Secretary of State Julian Smith at Stormont on Monday.
"We got figures verbally from the secretary of state, obviously we are going to have to go off, and the Department of Finance will analyse those figures and see exactly what they mean in terms of a financial commitment," said Mr Murphy.
"I have to say my initial take on this is it falls way short of what was expected, and in that sense there is much more work to be done to try and secure a financial package which accurately reflects the commitments given by the British Government as part of this document that they produced that they told us to take or leave.
"They need to ante up."
Earlier, the First and deputy First Minister said funding outlined in the deal to restore the Assembly must follow "quickly".
Arlene Foster and Michelle O'Neill met with Prime Minister Boris Johnson and Taoiseach Leo Varadkar at Stormont on Monday.
Ms Foster said: "We need significant and sustained investment, not just this year but over a number of years."
Ms O'Neill said: "We have done our bit and I look forward to the fulfillment of the commitments made by the two Governments to let us get to work."
Speaking after holding meetings with Northern Ireland's newly-appointed Executive ministers, Boris Johnson said healthcare will be a priority for the investment from the deal to restore power-sharing.
He did not comment on reports that the ‘New Decade, New Approach’ agreement includes a financial package amounting to £2bn.
"I have heard the arguments made to me this morning,” he said. “We are listening very carefully and we will certainly do everything we can to support.
"It is about leadership, it is about getting the public the services they need, particularly in healthcare.
"We all know what has been happening, it hasn't been very easy over the past few years for the people of Northern Ireland but it is a moment of hope because they have now politicians who will make themselves accountable to the improvements they want to see."
Boris Johnson was greeted by DUP First Minister Arlene Foster and Sinn Féin deputy First Minister Michelle O'Neill outside Stormont Castle.
As they posed for photographs, Mr Johnson shook hands with Ms O'Neill and NI Secretary Julian Smith shook hands with Ms Foster.
Mr Johnson praised the efforts of politicians from all sides for showing leadership in reaching an agreement to end the three-year impasse.
"What's so great about today is that Northern Ireland politicians have put aside their differences, stepped up to the plate and shown leadership," he said.
"And that is a fine thing and the right thing and they will be able now to develop what is a very, very promising set of circumstances for Northern Ireland and for its people."
The PM went on: "Never mind the hand of history on my shoulder ... I see the hand of the future beckoning us all forward.
"And I hope that with goodwill and compromise and hard work on all sides it will be a very bright future indeed."
Taoiseach Leo Varadkar arrived at Stormont on Monday afternoon.
He first met with Boris Johnson, for a catch-up on the deal and "new prospects for Northern Ireland", then with the First and deputy First Ministers.
"The Good Friday Agreement is up and running again with power-sharing here in Northern Ireland," he said.
"I look forward to the North-South Ministerial Council meeting as soon as we have a new government in place south of the border, so that we can resume north-south co-operation, and the Prime Minister and I spoke a lot about how we can beef up east-west co-operation over the next couple of years."
Earlier, Mr Smith pledged major investment to alleviate problems in the region's struggling public services, but declined to confirm the sums involved until a deal was done.
The Irish government has also made financial pledges within the agreement to honour commitments to part-fund some north/south projects, such as the A5 dual carriageway and a redevelopment of the Ulster canal system.
Ms Foster said: “We had constructive meetings with the Prime Minister and the Taoiseach around the financial package required to implement the commitments in the deal signed up to by all parties in the Executive.
"We need significant and sustained investment, not just this year but over a number of years. This is crucial in ensuring transformation in areas such as health and also our road and water infrastructures.”
Ms O’Neill said: “I impressed upon both Boris Johnson and Leo Varadkar the importance of coming through with the funding promised as part of the deal.
"All Executive ministers are committed to working together to tackle some very serious issues in our society and across public services. But, quite simply, we need the money to make it happen.
"We have done our bit and I look forward to the fulfillment of the commitments made by the two governments to let us get to work.”