The top designers, who are also gay and were once a couple, had made their remarks to Italian magazine Panorama in an interview published last week, reported E! online.
"You are born to a mother and a father. Or at least that's how it should be. I call children of chemistry, synthetic children. Rented wombs, semen chosen from a catalogue," Dolce had said.
"And shame on you for wagging your judgmental little fingers at IVF - a miracle that has allowed legions of loving people, both straight and gay, to fulfill their dream of having children.
"Your archaic thinking is out of step with the times, just like your fashions. I shall never wear Dolce and Gabbana ever again. #BoycottDolceGabbana," said the Grammy-winning singer-songwriter.
John and Furnish, who tied the knot in England in December, are parents to sons Zachary Jackson Levon Furnish-John, 4, and Elijah Joseph Daniel Furnish-John, 1, who were both born to a surrogate mother.