The Italian ANSA newsagency reported that "meticulous" security checks would be "strengthened" and "intensified" and enforced over an extended area, but the measures would be applied discreetly so as "not to disturb the prayers".
The Pope has expressed deep regret that a speech he gave in Germany implicitly linking Islam to violence had offended Muslims.
But he stopped short of retracting his remarks, arguing they had
been misinterpreted.
Muslims across the globe were outraged by the remarks.
A hardline cleric linked to Somalia's powerful Islamist movement has called for Muslims to "hunt down" and kill the Pope.
An armed Iraqi group has threatened to carry out attacks against Rome and the Vatican.
The leader of Egypt's Muslim Brotherhood, Abdel Moneim Abul Futuh, says the Pope has not been sufficiently contrite.
"This is not an apology," he said.
"The Vatican secretary seems content to confirm that the Pope is sorry because his remarks were misinterpreted.
"But they were not misinterpreted. The Pope made a mistake, he must recognise it and apologise."
The Pontiff is due to give his traditional Sunday address at midday (2000 AEST) from the balcony of his summer residence at Castel Gandolfo, just south of Rome.
Benedict XVI made the remarks that sparked the current furore on Tuesday during a speech Regensburg University.
Critics said he painted Islam in a violent light, particularly with reference to jihad or "holy war".
The Pope also quoted a 14th century Byzantine emperor who said innovations introduced by the Prophet Mohammed were "evil and inhuman".
In his statement on Saturday, the Pope said that in citing the emperor he had not meant "to make that opinion his own in any way".