However, Monchengladbach have pushed through a deal for the 25-year-old, who has penned a five-year contract with the Bundesliga side.
Sporting director Max Eberl said: "We're extremely glad that this transfer has gone through and we were able to sign Alassane despite a lot of competition from various other well-known clubs.
"Thankfully for us, he wanted to come to Borussia at all costs. He's a versatile, quick and clever forward who has put his talent on full display in Ligue 1 and the Europa League."
Plea will spend his first period outside of French football, having join Nice from Lyon back in 2014.