Marseille's players were frustrated from Roberto De Zerbi's departure on Wednesday, just days after a humiliating 5-0 loss at Paris Saint-Germain.
Fans showed their anger at the Stade Vélodrom as banners called for American owner Frank McCourt and president Pablo Longoria to leave in what were empty stands.
Greenwood has enjoyed another successful season with 23 goals to his name across all competitions with the French giants but as tensions increase, his future looks increasingly shaky according to reports.
With 45 goals in 69 games since signing for the French side, United will be hoping the England star can attract attention from a bigger side as they aim to collect cash from his sale.
According to The Telegraph, the clause is believed to be in region of 40-50%, entitling United to that percentage of the profits on any future sale.
Marseille signed Greenwood for around £26.5M, meaning 40-50% of profit over that figure will end up in United’s pockets.
Marseille have not won a trophy since the now-defunct League Cup in 2012 and the former United striker may be looking towards his future as the summer approaches.
De Zerbi has been linked with the Manchester United job, with the club looking to appoint a new head coach in the summer despite interim manager Michael Carrick overperforming.