Reports emanating from France on Tuesday suggested that the North-East outfit had agreed a £6.3m deal with the Ligue 1 giants for the 24-year-old.
Now, Pardew claims that negotiations are underway with the player himself, while also revealing that a deal to sign Netherlands defender Daryl Janmaat is "pretty close" to completion.
When asked about Riviere following United's 2-1 pre-season defeat to Oldham Athletic, he told reporters: "It's another one that we're talking to. He's a player that we have some interest in."
He added regarding Janmaat: "That's pretty close, but that's as good as I can say at the moment. I've been involved in the [Oldham] game, so I don't know the detail of it."