An official at the Council of Europe urged Serbia on Thursday to reconsider a ban on a gay pride event on Saturday for the second consecutive year.
Keith Whitmore said Belgrade should respect the right of gay people to free assembly.
Serbia is a member of the Council.
The European Commission earlier warned that the decision went against fundamental human rights upheld by the EU. Serbia won EU candidate status earlier this year.
The 2011 Belgrade Pride parade was banned at the last moment out of fear of a repetition of violence in 2010, when dozens of people were injured and arrested when protesters opposed to the parade clashed with police.
Prime Minister Ivica Dacic described the ban on this year's event as a "victory for Serbia".
''Nobody will be telling anyone what should happen in Belgrade, be it the EU or any of the countries of the world, or any extremist or radical organisation," he said.
"This is not about freedom of expression, this is a direct provocation that can destabilise relations within the country," Mr Dacic said.