Health Minister Robin Swann has said he is "deeply concerned" about the postponement of cancer procedures.
It comes after it emerged that 106 people had cancer procedures cancelled in the Belfast Trust area.
"I have always made clear that I expected to see red flag and cancer procedures protected as much as feasibly possible," Mr Swann.
Meanwhile, the Royal College of Emergency Medicine has warned cancer patients are attending A&E.
It has said that some of those attending have Covid-19.
Speaking on behalf of the college, vice-president Dr Paul Kerr said the health service must be able to adapt to deal with Covid and other emergencies.
It is because scheduled appointments elsewhere are being cancelled.
In a statement on Friday evening, the health minister said from next Monday he had asked for all cancer patients who have had their surgeries cancelled in recent days to be provided with a new date.
Mr Swann said the ability to provide these services, including the appropriate post-operative care, was dependent on the number of Covid-19 hospital admissions, the demand for ICU beds, and the availability of specialised staff.
"That is why stamping down on Covid-19 infection rates is now more critical than ever as reducing our rates helps us to protect those cancer and other vital services," he said.
He also confirmed the shielding of "clinically extremely vulnerable people" would remain paused, a decision which had been reached after discussions with Chief Medical Officer Dr Michael McBride.
'12 hours for a bed'
In an interview with BBC News NI, Dr Paul Kerr said that surgeries being cancelled, including cancer surgeries, must be addressed by the Department of Health.
The Belfast Health and Social Care Trust apologised after more than 100 people had cancer procedures cancelled.
This week a joint statement from the Royal Colleges in Northern Ireland urged the public to follow public health advice in order to help protect services - especially elective surgeries.
Mr Kerr said he watched cancer patients sitting in emergency departments this week who clearly should not have been there.
"At times we have seen over 200 patients [across all of Northern Ireland's emergency departments] waiting over 12 hours for a bed, and amongst those patients there have been perhaps 30 to 40 positive Covid cases at times," he said.
"Amongst those patients there have been many who have cancer. Perhaps those patients are in some kind of crisis, perhaps they are post-chemotherapy and unwell, or perhaps they themselves unfortunately have caught Covid."
Mr Kerr said there must be a plan in place to address all the outstanding issues that were raised in government health strategy documents like Transforming Your Care.
In particular, he said work force planning - which looks at staffing numbers and the suitability of staff to fulfil roles within the service - needed to be addressed.
"I think there's a plan but I mean we cannot change, we can't recruit nurses or make beds overnight so we are responding to an emergency situation where we are at the very height of a pandemic," he said.
"So we do the best we can on both sides of the equation, both in terms of the operations that patients need and the emergencies that patients present to hospitals with."