Enrique Gomez Bastida, director of the Spanish Agency for the Protection of Health in Sport (AEPSAD), said until all the facts are known no sanction can be put in place.
According to the Drip Doctors clinic, Nasri received its 'Immunity IV Drip', which involves one litre of hydration and is designed to "combat superbugs and common viruses".
However World Anti-Doping Agency rules state that there is a 50ml limit for active athletes.
Nasri is due to return to Spain this week after spending part of LaLiga's winter break in the United States.
A spokesman for the Spanish club said Sevilla had no information beyond what had been reported in the media.