Francis, 88, has been in Rome's Gemelli hospital for two weeks after being admitted on February 14 with a severe respiratory infection that triggered other complications.
"This afternoon ... the Holy Father experienced an isolated bronchospasm crisis," said the latest detailed update about the pontiff's condition.
The Pope, it said, also had "an episode of vomiting with aspiration and a sudden worsening of the respiratory condition".
He then received the help of "non-invasive mechanical ventilation," it said.
Francis, said the statement, "has remained alert and well-oriented" and is continuing his treatments.
Friday's news followed three days of more positive updates, with the Vatican saying previously that the Pope had been showing a "slight improvement" as he fights what has been termed a "complex" infection caused by two or more micro-organisms.
A Vatican official, who did not wish to be named because he was not authorised to discuss the Pope's health, said the Pope's breathing issue on Friday did not last a long time.
His doctors are expected to take 24-48 hours to evaluate how the episode will impact the state of his clinical condition, the official said.
The Pope has not been listed in critical condition for the past two days.
The Vatican has not said how long the Pope will remain in hospital but it announced on Friday that Francis would not lead the annual Church service next week to open the Christian season of Lent.
The March 5 service, known as Ash Wednesday, starts the 40-day period leading up to Easter Sunday.
It will instead be entrusted to a senior Vatican official.
Francis, who has been pontiff since 2013 and is often described as working himself to exhaustion, has continued leading the Vatican from the hospital.
Staff appointments requiring his approval are announced daily.
On Friday, the Vatican released a papal letter to participants in a Church training course in Rome, which was signed by Francis with a note to say it was sent "from Gemelli hospital".
Cardinal Michael Czerny, head of the Vatican's development office, said in an interview with Italy's La Stampa newspaper that Francis was getting better, albeit "slower than what we would like".
Francis has suffered several bouts of ill health over the past two years.
He is prone to lung infections because he developed pleurisy as a young adult and had part of one lung removed.
Double pneumonia is a serious infection of both lungs that can inflame and scar them, making it difficult to breathe.
The Vatican said Francis suffered a "prolonged asthma-like respiratory crisis" last Saturday but there have been no repeats.
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