The 82-year-old pontiff was caught on camera being dragged to the floor as he proceeded down the main aisle in St Peter’s Basilica.
Although shaken, he got to his feet and continued with the late night service.
French Cardinal Roger Etchegaray, 87, broke a leg as he tried to stop the woman reaching the Pope.
The assailant, dressed in a red hooded sweatshirt, was arrested by the Pope’s bodyguards and was described by Vatican spokesman Federico Lombardi as “apparently unbalanced”.
He said she had tried – and failed - to carry out the same stunt 12 months earlier.
Vincent Nichols, the Archbishop of Westminster, said it was “surprising” that she had managed to reach the Pope and that security arrangements at the Vatican were now being reviewed.
Mr Lombardi played down the incident and said the Pope showed “great self-control and control of the situation”.
He went on: “It was an assault, but it wasn't dangerous because she wasn't armed.”
Cardinal Etchegaray was taken to hospital.