The 23-year-old has found the net nine times this term, making him the club's top goalscorer along with Radamel Falcao.
"Right now I'd say, yes, this is my best season. It's the first time I made such a good start, but I'm in a very good team, I play with a lot of good players and we're on a good run," he told reporters.
"I'm also at an age where I know my strengths and weaknesses. I'm just giving it my all and the hard work is paying off."
A former France Under-21 international, Riviere joined Monaco from Toulouse last year.