The prime minister has defended the recommended 1% pay rise for NHS staff and said the government has tried to "as much as we possibly can".
The proposal has sparked talk of industrial action and demonstrations were planned across England on Sunday, with senior Conservatives also speaking out.
However Boris Johnson defended the decision during a visit to a vaccination centre in Brent in north London.
The PM said: “I’m massively grateful to all NHS staff and indeed to social care workers who have been heroic throughout the pandemic.
“What we have done is try to give them as much as we can at the present time.
“The independent pay review body will obviously look at what we’ve proposed and come back.
“Don’t forget that there has been a public sector pay freeze, we’re in pretty tough times, we've tried to give the NHS as much as we possibly can.
"But my gratitude is overwhelming and I'm so grateful, particularly to the nurses."
ITV News Political Correspondent Shehab Khan explains why there may be flexibility on the government's position
The comments come after Education Secretary Gavin Williamson suggested the government would turn to public sector cutbacks to claw back pandemic spending through a period of “restraint”.
Mr Williamson said ministers had “put forward what we believe we can afford” for nurses during “difficult economic challenges”.
Teachers and others in the public sector will face a pay freeze, with NHS staff the only ones to be exempted following their efforts during the coronavirus crisis, he said.
He told Sky News’ Sophy Ridge On Sunday programme: “What we all recognise is that this is a period of making sure we have restraint right across the public sector.
“We’re facing almost three-quarters of a million people who are unemployed and we have in the context of that decided to exempt the NHS from the public sector pay freeze, which is the only part of the public sector that has been exempted from that.”
Asked about the prospect of a pay rise for teachers, he added: “We saw this year the largest pay increase for teachers since 2005.
“But there is going to be pay restraint, there is going to be a pay freeze for the coming year, but we are continuing to invest in schools.”
Labour labelled the NHS pay recommendation “reprehensible”, and argued that a 2.1% wage increase had been budgeted and legislated for in January 2020 when the NHS’s long-term spending plans were voted on in the House of Commons.
The proposal has sparked talk of industrial action and demonstrations against the proposals took place outside Downing Street in London and in Manchester city centre on Sunday.
Unions have warned it could see nurses leave the profession in their droves following the “slap in the face” wage review from ministers after 12 months on the front line of the Covid pandemic.
Senior Conservatives, including former health minister Dr Dan Poulter, who has been working on the NHS front line during the pandemic, have also broken ranks to criticise the 1% decision in recent days, along with senior Tory backbenchers Sir Roger Gale and Andrew Percy.
Labour shadow foreign secretary Lisa Nandy said the rise recommended by ministers to the independent health pay bodies amounts to a “real-terms pay cut” as it will be outflanked by inflation.
The UK’s fiscal watchdog, the Office for Budget Responsibility, is predicting consumer price inflation (CPI) will rise to 1.7% in the coming year.
A newly-qualified nurse earning a £24,907 salary would face a real-terms cut to the tune of £174 if the rise goes ahead, according to Labour.
And with personal income tax allowance frozen at 2021/22 levels for five years by the Chancellor at the Budget and council tax likely to rise in a host of areas next month, the Opposition party said a new nurse could find themselves £307 worse off by 2023.
Ms Nandy told Sky News: “The government, to be clear, is not planning a pay rise.
“That is a real-terms pay cut because it doesn’t keep up with inflation, and for nurses to be offered a pay cut is just reprehensible in our view.
“We think nurses deserve a pay rise this year and that should never have been something that was up for negotiation – this is a Government that has completely got its priorities wrong.
“If they can give a special adviser (Dominic Cummings) who broke the rules a 50% pay rise but then offer our nurses a real-terms pay cut, that is a Government that just has not understood who it is that is getting us through this crisis.”