The Swiss forward celebrated his 22nd birthday after Saturday's La Liga match in San Sebastian but finished the evening at a local police station after a heated argument with his partner.
Reports in the Spanish media suggested a police officer had to intervene to stop an argument between Seferovic and his partner.
"Real Sociedad has opened an internal investigation relating to the player Haris Seferovic in order to clear the facts from last night in San Sebastian," the Basque club said in a statement.
"Haris Seferovic has given a statement this morning at the summary court, with no charges laid against him.
"Real Sociedad is sorry that one of his players is immersed in incidents like this. At the conclusion of the investigation, the club will take relevant action."
Seferovic and his partner reportedly dismissed the incident as nothing more than a typical relationship squabble.
