The Tejano music group confirmed on its Facebook page De La Rosa and his driver were assaulted early Monday by an unidentified man outside Blur nightclub.
The assailant was apparently annoyed De La Rosa declined to have his picture taken with the man.
"The guy, from what I understand, is 6 feet and stocky and he sucker-punched the driver and Oscar," La Mafia manager Armando Lichtenberger told KHOU.com.
"He's angry," Lichtenberger said of De La Rosa. "He didn't get to defend himself at all."
The singer was treated at Memorial Hermann Hospital for his injuries and released.
No arrests had been made in the case.