Bush had been scheduled to visit the basilica of Santa Maria in Trastevere, as well as hold a round-table discussion with members of the lay Roman Catholic organization Sant'Egidio Community at their nearby headquarters.
Instead, the Sant'Egidio meeting will take place at the U.S. Embassy, White House deputy press secretary Tony Fratto said.
Italian interior ministry officials said the reason for the switch was logistical. Bush has a busy schedule already on Saturday and the stop in Trastevere would have taken extra time, they said.
Sant'Egidio spokesman Mario Marazziti said the relocation, which he said was for logistical as well as security reasons, would give the round-table participants more time to delve into important issues. Bush and Sant'Egidio are expected to discuss fighting poverty, AIDS and Africa, among other topics.
The Trastevere stop had always been seen by some as a security risk since it is a neighborhood full of hard-to-monitor narrow streets and winding alleys. Earlier this week, however, the top government official in Rome, Achille Serra, had confirmed the visit, announcing that parking and private car traffic would be barred in the neighborhood until after the visit ended.