Doctors taking industrial action on Thursday do not want to do anything to jeopardise their relationship with patients, the British Medical Association (BMA) said.
BMA chairman of council Dr Hamish Meldrum said that doctors' fight is not with patients but with the Government.
But thousands of routine appointments and non-urgent operations will be cancelled as doctors take industrial action for the first time in 37 years in protest over the Government's controversial pension reforms.
Mr Meldrum said he hoped that after today's day of action the union could reopen negotiations with the Government, adding that "nobody wants a repeat of this".
He told ITV's Daybreak: "I hope (the action) is not pointless and futile because we are very anxious to seek a resolution to this dispute and if this helps to highlight the problem and to get to that resolution then I hope it will have some point to it.
"Nobody is happy about taking any sort of action that impacts adversely on patients. There has been a lot of soul-searching at the BMA but we have to represent our members' views and nearly three-quarters of those who voted wanted to take this sort of action because of what was happening to their pensions.
"Nobody likes taking anything that will inconvenience patients and I know a lot of doctors who have taken this step very unwillingly. Of course doctors are not on strike today - all doctors are at their place of work, they will be seeing anybody who is urgent or who needs to be seen. It is not a strike in the normal sense.
"The nature of the work that doctors do, it is very difficult to do anything that won't have some impact on patients.
"We doctors have enjoyed a good relationship, high trust, with their patients and we don't want to do anything to get rid of that, but what we feel we've had is lack of trust from the Government.
"We negotiated a deal on pensions four years ago that meant that doctors would work longer, they would pay more and that they would take the risk of any future increase or impact of people living longer on the pension scheme and the Government has walked away from that deal.
"I hope that after today we can sit down and we can talk. Nobody wants more of this, nobody wants a repeat of this. I'm not out to inconvenience patients because of this. Our fight is not with patients it is with the Government."
Health Secretary Andrew Lansley urged doctors not to participate in the "pointless" strike, warning them it would achieve nothing.
"I know doctors don't want to go on strike. I hope they don't," Mr Lansley said on ITV1's Daybreak.
"I think if they have an argument and they're angry, they're angry with the Government and that's our job to represent the taxpayer and the public interest, and maybe we will have that argument.
"But I can't see why anybody thinks there is any benefit in penalising patients. It won't serve any purpose whatsoever."
NHS leaders also said patients should not be dragged into the dispute.
The BMA announced the action 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.
Accident and emergency departments and maternity services will run as normal, and tests for critical conditions such as cancer will be still available.
But some non-emergency hospital clinics, outpatient appointments and planned surgery may be postponed.
GP practices will remain open but some may postpone routine appointments which can be rearranged for another day.
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.
Up to 1.25 million GP appointments will be pushed into the days and weeks following the action, he said.
Local NHS managers have urged patients to use services only if there is an urgent need.
The BMA has more than 100,000 members, all of whom could take part in the action. However, early polls suggest as few as 22% of doctors will be participating.
The last time doctors took action was in 1975, when consultants suspended goodwill activities and worked to contract over a contractual dispute, and junior doctors worked to a 40-hour week because of dissatisfaction with the progress of contract negotiations.