"We reject the discourse that Mr Torra has used repeatedly," SOS Racisme Catalunya, an independent association, said in a statement.
"A dangerous, irresponsible and unacceptable discourse, based in prejudices," the body said, adding it would denounce any potential "racist stances."
Handpicked by former Catalan leader Carles Puigdemont, who was deposed by Madrid after he and other separatist lawmakers declared independence in October, Torra has been severely criticised for a series of tweets and articles written in the past years.
His rivals say these demonstrate a "xenophobic," "supremacist" and "discriminatory" form of nationalism.
The allegations could harm the Catalan separatist movement which has always strived to differentiate itself from radical, xenophobic nationalisms that have arisen elsewhere in Europe.
- Hardline separatist Torra appointed leader of Catalonia
- PROFILE: Quim Torra, the Catalan separatist anointed by Puigdemont
In a series of articles published online, for instance, Torra said it wasn't "natural" to speak Spanish in Catalonia. He also described Spain as "a country that exports misery" and slammed those who don't defend the Catalan language and culture as "scavengers, vipers and hyenas."
A since-deleted tweet he posted in 2012 also said: "The Spanish are coming to monitor us, out of here once and for all!".
"His ideology is perfectly clear," Ines Arrimadas, the leader in Catalonia of the centre-right, anti-independence Ciudadanos party, said Monday.
"He defends xenophobia, he defends a discriminatory identity."
Most inhabitants in Catalonia, a rich region in northeastern Spain, speak Spanish and Catalan fluently.
It is also estimated that more than 60 percent of the region's 7.5 million inhabitants originate from other parts of Spain.
Torra has repeatedly apologised for the comments.