In an interview with Vogue, the singer-entrepreneur slammed Trump for his responses to the El Paso and Dayton mass shootings earlier this year, reports variety.com.
At that time, Trump called the shootings an act of "cowardice", Rihanna tweeted that he should have labelled them as "terrorism" instead.
"It is devastating. People are being murdered by war weapons that they legally purchase. This is just not normal. That should never, ever be normal. And the fact that it's classified as something different because of the colour of their skin? It's a slap in the face," said Rihanna.
"It's completely racist. Put an Arab man with that same weapon in that same Walmart and there is no way that Trump would sit there and address it publicly as a mental health problem. The most mentally ill human being in America right now seems to be the president," she added.
The singer also discussed her inspiration for her next album, saying that "reggae always feels right to (her). It's in (her) blood".
"I like to look at it as a reggae-inspired or reggae-infused album. It's not going to be typical of what you know as reggae. But you're going to feel the elements in all of the tracks," she said.
"It doesn't matter how far or long removed I am from that culture, or my environment that I grew up in. It never leaves. It's always the same high. Even though I've explored other genres of music, it was time to go back to something that I haven't really homed in on completely for a body of work," she added.