BERLIN — The United Nations’ human rights office is voicing concern about the risk of further violence in Venezuela as the country prepares for a vote to start rewriting the constitution, and about a new ban on political protests.

Opposition leaders are urging Venezuelans to boycott Sunday’s election for delegates to an assembly to rewrite the constitution. Officials announced security measures including an order barring political protests through Tuesday.

Liz Throssell, a spokeswoman for the U.N. High Commissioner for Human Rights, said in Geneva Friday that “the wishes of the Venezuelan people to participate or not in this election need to be respected.”

She urged the government to manage any protests “in line with international human rights norms and standards” and also called on those opposing the election to do so peacefully.