Pope Francis has instructed his new "princes of the church" – among them Cardinal Vincent Nichols, the archbishop of Westminster – to avoid "intrigue, gossip, cliques, favouritism and partiality" as they don the Roman Catholic church's prized red biretta.

Speaking in St Peter's basilica a day after he created 19 new cardinals, the Argentinean pontiff strictly exhorted the men to reject the habits of a royal court that have in recent years come to be associated with parts of the Roman curia, or Vatican bureaucracy.

Looking up from his notes to address the massed ranks of cardinals, he told them: "A cardinal – I say this especially to you – enters the church of Rome, my brothers, not a [royal] court. May all of us avoid, and help others to avoid, habits and ways of acting typical of a court: intrigue, gossip, cliques, favouritism and partiality."

Nichols, 68, is one of 16 new "cardinal electors" who are not yet 80 and are therefore young enough to be likely to vote in the next papal conclave to elect Francis's successor. The remaining three prelates are over 80. One, in fact, Cardinal Loris Capovilla, 98, was unable to attend the ceremony because of ill health.

Cardinal Vincent Nichols attends the mass with other newly appointed cardinals. Photograph: Franco Origlia/Getty Images

In a homily on Sunday, Francis made it clear there was no longer any room for shortcomings for those he had chosen to become his first entrants to the college of cardinals. "To be saints is not a luxury. It is necessary for the salvation of the world. This is what the Lord asks of us," he said.

In what some said amounted to a code of conduct, he added that cardinals needed to embody holiness "with greater zeal and ardour".

"We love, therefore, those who are hostile to us; we bless those who speak ill of us; we greet with a smile those who may not deserve it," he said. "We do not aim to assert ourselves; rather, we oppose arrogance with meekness; we forget the humiliations that we have endured."

He added: "This is the attitude of a cardinal, this must be how a cardinal acts."On Saturday, at a consistory in which Francis created his new cardinals, Nichols, leader of the Catholic church in England and Wales, knelt before the pope as he received the famed red biretta. He was told his titular church in Rome – of which he will now become a "cardinal protector" – would be St Alphonsus on the Esquiline Hill, dedicated to the Italian founder of the missionary Congregation of the Most Holy Redeemer.

Designed by Scottish architect George Wigley in the 19th century, the neo-Gothic building houses a celebrated Byzantine icon of the Virgin Mary entitled Our Lady of Perpetual Help.

On Sunday, Father Luciano Panella, rector of the church, said he had been introduced to Nichols at St Peter's and was now looking forward to planning his official welcome. "We are very happy about this nomination," he said. Previously, St Alphonsus's titular cardinal had been Anthony Bevilacqua, a former archbishop of Philadelphia who died in 2012, leaving the post in Rome vacant.

Pointing to a photograph of the late American cardinal hanging on the wall, Panella smiled and said: "We'll have to get a one of the new cardinal now."