Yes. The Ferengi are frequently discriminated against.
Dr. Reyga was a young Ferengi Scientist. A fair bit of the plot of the TNG Episode "Suspicions" deals with the trouble he's had being taken seriously. He refers to the scientific community beyond just the Federation. The delegation brought to see his discovery include a Klingon, and a Takaran (not likely a Federation member). None of which view him with an open mind. Reyga himself mentions his people's reputation. It's not his age, but specifically his species.
"This is an opportunity I would never have had without you, and I promise you, I'll never forget it."
"Some of the scientists still seem a little doubtful, but after the demonstration I'm sure they'll come around."
"Well, if there's anything I'm used to, it's skepticism. After all, a Ferengi scientist is almost a contradiction in terms. No, don't deny it. I know how the Ferengi are regarded."
-- Reyga and Beverly Crusher
This reputation isn't just confined to the Federation. Here's an exchange between Kira (Bajoran) and Jadzia (Federation-Trill). Note that Jadzia, even as a Federation Scientist, doesn't argue with Kira's negative beliefs, just says they can still be fun.
"They're greedy, misogynistic, untrustworthy little trolls, and I wouldn't turn my back on one of them for a second."
"Neither would I. But once you accept that, you'll find they can be a lot of fun."
– Kira Nerys and Jadzia Dax, 2370 ("Rules of Acquisition")
The Ferengi have an ideology diametrically opposed to the Federation, and Humanity in particular,
The Federation has abolished currency and want. The Ferengi have built their entire culture around money and profit.
Greed is eternal.
-- Rule of Aquisition #10
The Ferengi also consider women to effectively be property. Marriage is a temporary contract between the Husband and the woman's Father. This is very much opposed to the Federations declared abhorrence of slavery or inequality.
Finally, the Ferengi and Federation have experienced open conflict for a fair period of their relationship. TNG shows the first recorded visual contact with Ferengi by the federation which, although it ended peaceably, included ship-combat. By the end of DS9 they have only been known for 12 years (first visual contact 2364, end of DS9 2376). Picard destroyed a Ferengi vessel while captain of the Stargazer, and several times throughout the series is attacked by Ferengi.
Riker has fair reason to distrust the Ferengi, as all of his experience has been negative up until the point of your example in the 5th season. Their initial meeting is combative, after the Ferengi stole Federation property. Daimon Bok is an antagonist in a first season episode, and again in the 7th. Picard is taken prisoner by another Ferengi in season 3 while on vacation. Even after your example, his suspicions are proven correct when the Ferengi attempt to buy a woman on the ship, and end up injuring an Ambassador.
This is clearly prejudiced on Riker's park. Even if his experience is entirely negative, he is judging these Ferengi on their race alone. Other characters present similar distaste of the Ferengi.