The chief executive said a “well-established and robust” plan was in place, but that NHS leaders had been “distracted from doing our day job”.
Prime Minister Sir Keir Starmer has also described the strikes as “irresponsible”.
They were planned after the government offered a fresh deal which included increasing speciality training posts and covering out-of-pocket expenses, like exam fees.
The offer did not include any promises on pay which, for resident doctors, has been increased by almost 30% in the past three years.
However, the BMA argued that, despite the rises, resident doctors’ pay was a fifth lower than it was in 2008, once inflation was taken into account.
Resident doctor leader Dr Jack Fletcher said: “Tens of thousands of front-line doctors have come together to say ‘no’ to what is clearly too little, too late.”
He added the union was “committed to ensuring patient safety” and would be in close contact with NHS England throughout the industrial action.