The 40-year-old has a seven-year-old son, Aurelien, with ex-boyfriend Raphael Enthoven, and she wants to give him a brother or sister before she's too old.
"I'd love to have children with Nicolas. I hope to, if I am young enough. It would be a dream," she told Vanity Fair magazine.
However, she insisted that she will not undergo fertility treatment to help her conceive - preferring to let nature choose.
Bruni added: "If it comes I would be the happiest person in the world, but if it doesn't come, I'm not going to tempt the devil."
After a whirlwind romance, Bruni married Sarkozy in February, this year.