Sadiq Khan has been challenged by a pensioner who said the decision to scrap free bus travel at peak times for over-60s has left her in "limbo" and unable to afford to travel.
Under the terms of a Government bailout amid the coronavirus pandemic, pensioners will no longer be allowed to travel for free before 9am.
Speaking to the mayor of London on LBC radio, a woman called Maureen demanded to know when the policy would be reversed.
Maureen, who has lived in London for 55 years, said: "I've got to help my daughter with her children. It's costing me £10 a day. It's really inconvenient for me."
Mr Khan replied: "We tried to resist this one."
But Maureen interrupted and said: "I hear from you that every journey matters - obviously my journey doesn't matter."
Mr Khan apologised and said: "I'm really sorry you have now got to pay to use buses before 9am...when we do the deal with the Government in October, we will try and make sure we can get this changed.
"It has affected people like you, Maureen, so when we negotiate with the Government in the next part of the deal, which comes to an end on October 15 or 17, we will try and see that the next part of the deal allows people like you to use a freedom pass before 9am."
Mr Khan said the decision was made to cut the number of passengers using public transport during rush hour, rather than as a money-saving exercise.
"But you're right, people like you who have to use it because you have got to take your daughter on journeys, are being penalised and you probably can't afford to pay the fare before 9am."
Maureen said she can't afford the bus fare, adding: "My daughter is a teacher, she can't afford to pay me. What do I do? I'm in limbo."
Mr Khan said the measure will be in place until at least mid-October.
"We're quite clear with the Government that it's got to be temporary," he said. "We don't want this to be a permanent thing."
As part of the deal, Mr Khan was forced to hike the congestion charge to £15 a day, while free travel for 1.5 million London schoolchildren was temporarily axed.
Mr Khan said at the time: "It was the only deal the Government put on the table and I had no choice but to accept it to keep the Tubes and buses running."
