An opposition group dubbed the Bersih 2.0 coalition called for electoral reforms in the country, saying the current system was riddled with fraud. Malaysian police fired tear gas on demonstrators during the weekend and arrested more than 1,600 people.
Opposition leader Anwar Ibrahim was among those wounded in the crackdown, the BBC reports.
Phil Robertson, deputy Asia director at Human Rights Watch, said it was apparent that civil liberties weren't sacred when coming up against state authorities.
"Apparently in Malaysia, freedom of speech, assembly and association are only permissible when they support the government," he said in a statement.
Mark Toner, a spokesman for the U.S. State Department, echoed those concerns by stating that Washington was bent on advocating basic freedoms across the globe.
"Obviously, we stand for and continue to stand for the right for people to freely express their democratic aspirations and express their views freely," he told reporters during his regular briefing.
Malaysian officials said most demonstrators were released shortly after they were detained.