EU: "This was not a vote on the constitution," Mr Giscard said in an interview with the New York Times on Wednesday which pointed the finger clearly at the current incumbent of the Élysée.
"The French message was, 'We want change in our political leadership'," he said.
Mr Giscard, not a fan of Jacques Chirac, accused the president of not responding early enough to popular anger at his government and of confusing voters by asking too much of them in getting them to vote on the lengthy and complex third part of the treaty, a compendium of existing, already agreed EU policies.
Neither Mr Chirac nor other European leaders have had a strategy for ratifying the constitution, he said. "The present generation of leaders, whatever their strengths, never put Europe at the top of their agenda."
He told the New York Times that a crucial turning point for the constitution in France came last March when he phoned Mr Chirac to warn him not to send the entire three-part 448-article document to every French voter.
He said Mr Chirac refused, citing legal reasons. "I said, 'Don't do it, don't do it'," Mr Giscard said. "It is not possible for anyone to understand the full text."
Mr Giscard said he now believed the French parliament should have ratified the constitution, even though he backed the idea of a referendum.
He also told the New York Times that had European Union leaders not left open the possibility of full membership for Turkey, the constitution probably would have passed in France. He said the ratification process should continue across Europe and envisioned a sequence of events in which most members passed what he referred to at one point as "my document".