Dozens of people attended demonstrations. Some lay in the street with chalk outlines of their bodies drawn on the ground under a fake street sign that read "AIDS Victims' Square". Several carried air-filled condoms tied into a cross.
Lucie Uzzeni, an activist for Act Up, an organisation that campaigns for greater Aids awareness, told LCI television: "We are demonstrating against Bertrand Delanoe. He took this decision. He voted in favour of honouring a man who for us is the symbol of millions of deaths in the world."
Bertrand Delanoe, the mayor of Paris, attended a ceremony to unveil a sign bearing the square's new name, John Paul II Square. It was previously named after the cathedral, which is one of the French capital's most visited monuments.
Supporters credited the Polish Pontiff with playing a major role in the fall of Europe's Iron Curtain, but liberal Catholics said his support for human rights causes clashed with his opposition to married priests, women clergy, contraception and abortion.
Delanoe defended the decision to name the square after Pope John Paul, who died last year.
He said: "I think the message of John Paul II was, to a large extent, universal. For example, for freedom - the freedom of eastern Europe."