Argentine Prestianni will miss Wednesday's return leg at the Santiago Bernabeu, with Real Madrid holding a 1-0 lead from the first leg in Lisbon.
UEFA have stated that a longer suspension could be handed out, with the governing body's Ethics and Disciplinary Commission continuing their investigation.
"This is without prejudice to any ruling that the UEFA disciplinary bodies may subsequently make following the conclusion of the ongoing investigation and its respective submission to the UEFA disciplinary bodies," a statement regarding the provisional ban reads.
Benfica have defended their player since the incident took place and have now confirmed that they will appeal the ruling.
“The club regrets being deprived of the player while the process is still under investigation and will appeal this Uefa decision, even if the applicable timelines are unlikely to have any practical effect on the second leg of the Champions League playoff," the club said.
“Benfica also reaffirms its unwavering commitment to combating all forms of racism and discrimination - values that are part of its historical identity and reflected in its daily actions, its global community, the work of the Benfica Foundation, and major figures in the club’s history, such as Eusebio.”
More to follow