The government should hold last-minute negotiations with doctors planning to strike on Thursday, shadow health secretary Andy Burnham said.
He added that patients should not be made to suffer because of the dispute over pension reforms, and urged doctors to "step back" from the action, the Press Association reported.
Mr Burnham said: "We urge them to step back even at this late stage.
"We understand the level of anger that the doctors have with the government but patients shouldn't be made to suffer.
"There are other ways of communicating the strength of feeling and we would urge them to use those.
"To the government that promised to listen to doctors, we say to them that they should get back round the negotiating table today."
Health secretary Andrew Lansley wrote to the British Medical Association (BMA) on Tuesday telling them that a £68,000-a-year pension was his final offer.
He urged the union to think again about the action.
"The BMA say doctors feel that changes to their pension scheme are unfair and unnecessary," he said.
"This suggests that they do not feel any change to their pensions arrangements are justified - but change is necessary and our proposals are fair."
According to Mr Lansley, the planned action could see up to 30,000 operations cancelled, 58,000 diagnostic tests postponed and 200,000 outpatient appointments rescheduled.
Mr Lansley also said up to 1.25 million GP appointments would be pushed into the days and weeks following the action.
The BMA announced the strike last month after it accused ministers of pressing ahead with "totally unjustified" increases to pension contributions and a later retirement age for doctors even though a deal on pensions was agreed four years ago.
All non-urgent work will be postponed, the BMA said, adding that although the action will be disruptive, doctors will ensure patient safety is protected.
Doctors will see anyone who is ill, or who believes they are ill, on the day of action but will not do paperwork.
Local NHS managers have urged patients to use services only if there is an urgent need.
Most doctors will be taking industrial action for the first time, with the last dispute almost 40 years ago.
A BMA spokeswoman said: "Doctors do not want to take industrial action - they have not done so for 40 years.
"We deeply regret the disruption this will cause for patients - though we are adamant that patient safety will not be affected. Thousands of doctors have said that they will take action tomorrow because there is no other option left to get their voices heard by government over the wholesale changes being imposed on an already reformed NHS pension scheme.
"We continue to implore the government to work with us and other health unions to find a fairer approach instead."
Suggested For You
Get top stories and blog posts emailed to me each day. Newsletters may offer personalized content or advertisements. Learn more