This incident was in Texas, the state where Manziel earned the nickname "Johnny Football."
Fort Worth police put out a press release about officers being dispatched to an apartment around 2 a.m. Saturday "in reference to a report of a possible assault."
Police didn't find whoever called in the report, "but did make contact with a 23-year-old female who stated that she was involved in a disturbance with her ex-boyfriend (23-year-old male suspect) earlier in the evening in Dallas."
A preliminary investigation "determined that a possible assault had occurred in [Dallas] or multiple jurisdictions," Fort Worth Police said.
The woman, who was not identified by name, did not cooperate with officers, who "were unable to locate a crime scene" in Fort Worth.
"The complainant also advised our officers of concerns that she had regarding the well-being of her ex-boyfriend," police said. Officers eventually found him to be "safe and in no danger."
The Fort Worth news release does not name either the woman or man involved. But in tweeting out the report, Fort Worth police said it was "regarding Johnny Manziel."
Dallas police later released a statement of their own about "a possible offense that may have occurred within the Dallas city limits."
"We are in the preliminary stages of the investigation and have no further information at this time," Dallas police said. "When additional information becomes available it will be released as appropriate."
There was no immediate comment from Manziel.
His current pro team, the Cleveland Browns, declined to speak about the matter.
NFL spokesman Greg Aiello said simply, "We are aware of the incident and looking into it."
This marks the latest time that the quarterback, a Heisman Trophy winner at Texas A&M University and first-round draft pick with the Browns, has had a run-in with the law.
Another happened October 12 in Avon, Ohio.
In dashcam video, a police officer pulled up to Manziel and a woman -- later identified as his then-girlfriend -- parked along the side of a two-lane road, telling them about "numerous calls" about their speeding BMW. The woman claimed Manziel hit her several times to prevent her from getting out of the vehicle, while downplaying the incident.
"I don't want to make a big deal," she said.
The then-girlfriend later tweeted that "J & I are good" and thanked those who "stopped to check on us and call the police."
"I could see how it may have looked," she wrote. "Anytime anyone sees a guy and a girl arguing on the side of a road they should definitely stop, you never know what that could be. Fortunately, it was just an argument, it was private, and we are all good!"
No charges were filed in that incident, and it was not clear whether it involved the same woman mentioned in the latest Texas incident. Still, it heightened the spotlight on Manziel, who has been long accused of partying too much and squandering his talents in the process. He went to an alcohol- and drug-treatment center in Caron, Pennsylvania, in early 2015, soon after the end of his rookie NFL season.
"I take full responsibility for my actions and it's my intention to work very hard to regain everyone's trust and respect," Manziel said after getting out of rehab
."I understand that will take time and will only happen through what I do and not what I say."