The EU pushed Iran on Monday to guarantee the right to protest as authorities have moved to crack down on days of unrest across the nation.

Protests broke out Thursday and have quickly grown to become the biggest test for the regime since mass demonstrations in 2009.

"We have been in touch with the Iranian authorities and we expect that the right to peaceful demonstration and freedom of expression will be guaranteed," a spokeswoman for the bloc's foreign policy chief Federica Mogherinisaid in a statement.

"We will continue to monitor developments," the spokeswoman added.

The latest demonstrations on Monday came despite President Hassan Rouhani's vow that the nation would deal with "rioters and lawbreakers".

The total death toll linked to the protests currently stands at 13. Authorities have confirmed more than 400 arrests since the outbreak of the unrest, of whom around 100 have been freed.

Rouhani came to power in 2013 promising to mend the economy and ease social tensions, but high living costs and a 12 percent unemployment rate have left many feeling that progress is too slow.