La Liga said it had found no evidence Cadiz player Juan Cala directed racist language at Valencia's Mouctar Diakhaby during a game on Sunday.
Diakhaby reacted furiously after an altercation with Cala in the 28th minute of the game, stating the defender had used derogatory language related to the colour of his skin.
After a 25-minute break in play, the game continued, without the substituted Diakhaby, and Cadiz won 2-1.
Valencia's Diakhaby racism allegations being studied by lip reader - La Liga boss
Cala has denied the allegation and La Liga says it has not been able to source any evidence that he was guilty of the accusation.
The Spanish football league says it has analysed all available video and audio, and sourced a lip reading specialist, but the outcome was inconclusive.
"Following an analysis of the elements available to La Liga, it can be concluded that no evidence has been found of Juan Cala using the denounced language towards Mouctar Diakhaby," a Liga statement read.
"In concrete, all available television and digital archives from the game have been examined as well as the audio footage from the game, the images that were broadcast and what was shared on social media.
"In order to complete the report, a specialist company was hired to do a lip-reading analysis of the conversations and study of the players' behaviour."
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Valencia have responded by saying the report has "by no means changed our opinion on what happened in the game, and maintain our full support for Diakhaby".
In a statement, the club added: "Our objective is to see a change and an appropriate reaction to such a serious incident, and to see moves to change regulations and attitudes when it comes to facing these problems whenever they may occur.
"Valencia CF consider it positive that conversation has begun to establish new protocols that are necessary to combat racism in football. We are proud of Diakhaby, our captains, our players, our coach and his staff for their reaction during the game against Cádiz.
This was an unprecedented incident in football, but we are convinced that it will serve as an impetus for real change to the rules.
"Having reached this point, it is necessary to continue working with La Liga, the institutions and the rest of the club's to ensure that these types of racist incidents are never repeated."
Both the Spanish Football Association and Cadiz are holding their own investigations into the incident, and La Liga has provided its full report to all parties to help with their enquiries.
With additional reporting from Reuters
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