Speaking to broadcasters on Tuesday evening, Mr Barclay cited a “combination” of factors including the increased spread of viruses as the reasons behind long waits in A&E and for ambulances.
NHS leaders have said the pressure on the health service is “intolerable and unbearable” for both patients and staff.
Patients are currently enduring record waits for treatment in A&E while ambulance crews are spending hours queuing outside hospitals waiting to hand over patients, contributing to delays in responding to calls in the community.
Several NHS trusts have declared critical incidents in the past week, with strike action by nurses and paramedics set to increase pressure on the health service later this month.
Mr Barclay said: “There’s £500 million of investment this year going into tackling the pressure in terms of social care. So we’re putting more funding in. We’ve got more clinicians, we’ve got more staff working in the NHS.
“Of course there’s a range of factors that we need to do. There’s been particular pressures over Christmas because we’ve had a surge in flu cases, Covid cases and also a lot of concern around Strep A.”
Mr Barclay added that he was focused on “getting the people out of the hospital who don’t need to be there” in order to “speed up the ambulance handover delays.
On what reassurance he can give to people that the NHS is “safe”, Steve Barclay told broadcasters: “We are putting in more funding, we’ve got more staff, over 34,000 more staff working in the NHS, so there’s more nurses, more doctors, we have got an extra 7,500 going into social care, looking at greater support for domiciliary care…”
Analysis by the Standard found that ambulance crews lost more than 2,500 hours due to handover delays in the week up to December 25.
The target is for handovers to be completed within 15 minutes. Ambulance chiefs have warned that handover delays are leading to patients dying.
Hospitals are struggling to discharge patients and free up capacity in A&E as many beds are occupied by patients in need of adult social care who have nowhere else to go.
Ambulance staff are set to walk out on January 11 and 23 in a row over pay, while nursing staff will strike on January 18 and 19.
Royal College of Nursing general secretary and chief executive Pat Cullen said: “We are seeing A&E in a dangerous state, social care overloaded, primary care suffering and staff truly broken.
“The Government cannot blame the pandemic and other winter pressures for the crisis unfolding before our eyes – this has been a long time in the making yet the Government has consistently ignored warnings.
“It is painful and infuriating to be in this position – especially for patients and for our members who are struggling on the front line every day.
“One of the root causes is the ever-worsening workforce crisis, with nurses leaving in their droves because of a decade of real-terms pay cuts.
“Without enough staff, patients will never be safe. Yet the Prime Minister and his Government continue to refuse to even meet with us to talk about pay.”