The British government is being urged to step up and support people and families struggling with rising living costs.
It comes after the Irish Government announced a cut in excise duty on petrol and diesel on Wednesday.
The reduction will be 20 cent per litre on petrol and 15 cent per litre of diesel. A cut of 2 cent per litre on green diesel has also been agreed in the Republic of Ireland.
Read more: £200 Energy Payments NI: Deirdre Hargey confirms delay due to 'technical glitch'
The measure will be in place until 31 August and will cost €320 million (£268m). The reduction will reduce the cost of 60 litre tank of petrol by €12 (£10) and 60 litre tank of diesel by €9 (£7.50).
Sinn Fein's Stormont leader Michelle O'Neill has written to Prime Minister Boris Johnson seeking immediate action to help families struggling with the cost-of-living crisis.
Ms O'Neill said: "The cost-of-living crisis is crippling so many families. So many people now are struggling to heat their homes, put fuel in their cars, put food on their tables.
"There are things the British Government can do with immediate effect, with urgency, and I am calling on Boris Johnson to act now, to step up and deliver for families who are struggling right through this crisis.
"What we need to see is the duty on home heating oil scrapped immediately, what we need is a reduction on the tax on fuel prices, what we need to see is the National Insurance hike to be axed, what we need to see is the big corporations who are making profits off the back of the ordinary person, they need to be taxed and the money needs to be put back into the pockets of workers and families.
"And what we need to see is the changes stopped in the use of red diesel. These are things that can make a real practical difference to people's lives and I am urging the British Government to do those right now."
Earlier, DUP leader Sir Jeffrey Donaldson told the House of Commons that if the Chancellor sought to reduce VAT on "home heating oil", he would need the permission of the European Union.
Sir Jeffrey insisted "this cannot be right", claiming his constituents are being deprived of support because of the Northern Ireland Protocol.
He said: "At this time, households across all of the United Kingdom, including Northern Ireland, are struggling because of rapidly increasing home heating costs.
"In Northern Ireland, we are subject to EU VAT rules. This means that if the Chancellor of the Exchequer sought to reduce VAT on home heating oil, he needs the permission of the European Union and all 27 member states to do such an action.
"Surely, this cannot be right that my constituents are being deprived of the support they need from Government because of the protocol."
Northern Ireland Secretary Brandon Lewis said Sir Jeffrey was right in "highlighting just another one of the many areas where the protocol is creating real problems on the ground for people in everyday lives".
He added: "We must remember the protocol itself says it will not disrupt the everyday lives of people in their communities. He's given yet another example where the protocol itself and the implementation of it is doing exactly that. That has to stop."
The DUP pulled Paul Givan out of the First Minister post last month in protest against Brexit's Northern Ireland Protocol, forcing the resignation of Michelle O'Neill as Deputy First Minister.
Other ministers remain in place but they can only make some limited decisions as the full five-party Executive cannot meet. The Assembly is set to be dissolved later this month for fresh elections.
Stormont party leaders are due to hold a meeting on Thursday to discuss how to resolve funding issues and ease cost-of-living pressures.
SDLP deputy leader Nichola Mallon has already written to Communities Minister Deirdre Hargey proposing that a £200 energy payment support scheme is extended to all bill payers in Northern Ireland.
The scheme, which will make one-off £200 payments to help people on some benefits, launches on Friday.
Read more: Expert explains how to keep petrol and diesel costs down as prices rise in NI
Read more: Diesel and petrol prices across NI as they continue to soar
To get the latest breaking news straight to your inbox, sign up to our free newsletter.
