The nuptials will take place at St George's Chapel on May 19.
According to Entertainment Tonight, the group will be present at the wedding but will not perform.
"The girls were individually invited to attend the wedding, but there is no plan to have them perform," a source said.
"Although there is no plan to have the Spice Girls perform, it is a wedding and who knows what could spontaneously happen," the source added.
Kensington Palace revealed on March 22 that the official invitations for the wedding had been sent to approximately 600 guests. All of the guests were also invited to Queen Elizabeth II's celebratory reception at St George's Hall at Windsor Castle, but only about 200 friends and family members will go on to the second, private reception at Frogmore House hosted by Harry's father, Prince Charles.
Others stars who are confirmed to attend the couple's nuptials include Markle's "Suits" co-star Patrick J Abams, and her friend Priyanka Chopra.