The pope addressed tens of thousands of people from his balcony overlooking the square.
He told the crowd: "In the current conflict in Libya, may diplomacy and dialogue replace arms, and may those who suffer as a result of the conflict be given access to humanitarian aid."
Christians worldwide on Easter Sunday recall Jesus' resurrection, a sign of eternal life, following his crucifixion. This year, Easter fell on the same day in the Orthodox and Roman Catholic church calendars.
Benedict will return to the square in exactly one week to lead a crowd expected to be at least double Easter's turnout when he beatifies John Paul, putting the Polish-born, long-serving pontiff on the last formal step before eventual sainthood.
The Associated Press contributed to this report.