In the first response by the Vatican to a strong-worded letter - which was made public last weekend - the Holy See's secretary of state also encouraged greater dialogue within the Roman Catholic Church.
The letter, known as a "filial correction", claimed the pontiff had taken seven heretical positions concerning areas including marriage and moral life.
While conceding those who do not agree with Pope Francis have the right to express their concerns, secretary of state Cardinal Pietro Parolin added: "On these things one must reason and find ways to understand one another."
The letter came after Pope Francis issued his Amoris laetitia ('Joy of Love' in English) declaration last year which sparked fears among critics that he was opening the door to divorced and civilly remarried Catholics receiving Communion.
Among the signatories are Dr Joseph Shaw, a research fellow in philosophy at the University of Oxford, and former president of the Vatican bank, Monsignor Antonio Livi.
Speaking with Premier on Monday, Dr Shaw said: "It [the letter] represents an escalation, if you like, because it makes more explicit than before that what the pope seems quite clearly to be encouraging is incompatible with faith.
"It [the letter] sends the message that this is not acceptable to an increasingly large proportion of the Catholic faithful, and even if the pope chooses to ignore that it's something that's going to be taken into account by Curia officials."
Dr Shaw was one of fewer than 150 people to sign the letter.