"I would like to thank Rabiot whose contract expired on June 30. We would all like to wish him the best for the future," said Giuntoli.
Rabiot leaves Juve after five years in which he won the 2020 Serie A title and two Italian Cups. The midfielder has played 48 times for France, scoring four goals, and was a runner-up at the last World Cup in Qatar.
Rabiot played five times at Euro 2024, where Les Bleus were eliminated in the semi-finals by eventual winners Spain.
Italian media report that AC Milan and Real Madrid are among the teams interested in signing Rabiot, who reportedly refused a two-year contract extension worth 7.5 million euros (£6.3m) a season.
Giuntoli was speaking at Thiago Motta's first official press conference as new Juve coach. Motta takes charge of his first Serie A match as Juve boss when the Turin giants host promoted Como on August 19.
