The Colombian was wanted by every club in the game, but chose the newly promoted ASM earlier this month.
"I had the chance to meet [Falcao] in Dubai, and off the field he is very discreet. After that, despite his young age, he is already an experienced player and a great striker," said Abidal.
"I was very surprised by his choice, but I hope he will be proved right. This is a major new addition to the French championship. [The move] shows that Monaco have real ambitions for many years to come."