Nursing leaders and unions expressed anger last week when it emerged that ministers had recommended a 1 per cent pay rise.
Speaking on a visit to a vaccination centre in Brent in north London, the prime minister, who was himself hospitalised with Covid-19 last year, said he was “massively grateful” to NHS and social care staff.
They had been “heroic” throughout the battle against the coronavirus pandemic, he said.
But he suggested that his government could not afford to pay them more than 1 per cent, which critics say is a real-terms cut in salary.
Mr Johnson said: "What we have done is try to give them as much as we can at the present time,
“Don’t forget that there has been a public sector pay freeze, we’re in pretty tough times.”
He added: "My gratitude is overwhelming and I’m so grateful particularly to the nurses.”
Dame Donna Kinnair, general secretary of the Royal College of Nursing, said: “Boris Johnson is still failing to understand the situation he has stumbled into - more of these warm words for nurses are not going to cut it.
“When there are already tens of thousands of unfilled nurse jobs in the NHS, he’s pushing more to the door this weekend.
“The prime minister must put his money where his mouth is. NHS staff are worth it and there is overwhelming public support. His government can show it is listening and drop this plan.”
Labour has said nurses should receive at least a 2.1 per cent pay rise this year as a “bare minimum” denouncing the government’s offer of less than half that as “reprehensible”.
NHS leaders have pointed out that ministers budgeted for the higher amount last year, as part of a long-term plan for the health service.
Shadow foreign secretary Lisa Nandy told Sky News’ Sophy Ridge On Sunday that it was “reprehensible” that ministers were planning a real-terms pay cut that would not keep pace with inflation forecasts.
“In the NHS long-term plan, the Government budgeted for a 2.1% pay rise - that is what nurses were promised and last year (ministers) legislated for that in order to give nurses a cast-iron guarantee that after years of seeing their real-terms pay fall, that the Government would finally reverse that decision and start to see their pay increase,” she said.
“We think they ought to go into these negotiations at a bare minimum of honouring that promise of a 2.1% (increase) and then consider what more they can offer to our NHS staff who have done so much to put their families and themselves at risk every day going into work - some of them have died.”
She also accused the government of having its “priorities wrong”.
“If they can give a special adviser (Dominic Cummings) who broke the rules a 50 per cent 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,” she said.
Education secretary Gavin Williamson defended the 1 per cent offer saying ministers had “put forward what we believe we can afford” during “difficult economic challenges”.
Teachers and others in the public sector will face a pay freeze, he said, with NHS staff the only ones exempt because of their efforts during the coronavirus crisis.
Demonstrations against the proposals are planned outside Downing Street and in Manchester city centre later.