An ultra-nationalist rally failed to materialise on Sunday
An Australian tourist has become the second foreigner in four days to be attacked in Serbia's capital, Belgrade.
The 25-year-old man was reportedly targeted by two men in a public park and suffered head and face injuries.
A 28-year-old French football fan who was attacked by Serbian hooligans on Thursday remains in critical condition.
The attacks come amid concerns about a surge in extremist violence, with police arresting dozens of suspected members of far-right groups.
A gay march planned for Sunday was called off this week, when authorities said they could not guarantee its safety.
Serb nationalists had planned a "non-deviant" rally to coincide with the march, but reports said it only drew a handful of people.
Serbian TV station B92 reported that police were banning all public gatherings in the centre of the city to avoid clashes.
The Gay Pride march would have been the first in Belgrade since 2001. That parade descended into chaos amid widespread violence by mobs of protesters.
The justice ministry said that a total of 46 members of far-right groups, including a number of leaders of ultra-nationalist organisations, had been arrested, the Associated Press news agency reported.
Police said they were searching for a group suspected of attacking the Australian.
The state prosecutors office has said that 11 men could be charged with attempted murder for attacking French football fans after Thursday's incident.