The 30-year-old defender - who is currently on loan at boyhood club Estudiantes - has allegeding flouting Argentina's coronavirus lockdown rules, which are set to remain in place until at least May 10.
Images showing Rojo playing poker and smoking with friends were shared on social media by his brother Franco, and have since been deleted.
Recently it was revealed the footballer had been doing his bit to help those in need during the global pandemic.
Last month, Rojo had delivered food and drinks to over 200 families in La Plata, Argentina.
However, the unfortunate incident comes after Premier League stars like Aston Villa captain Jack Grealish, Everton striker Moise Kean and Manchester City's Kyle Walker have all been criticised for ignoring the UK government's advice.
Rojo - who isn't in United boss Ole Gunnar Solskjaer's plans - only played nine times for the Red Devils during the 2019-20 campaign before making the move to Estudiantes in January, but but an injury and the coronavirus crisis mean the 30-year-old defender made just one appearance before the league was suspended.