Military forces last month surrounded the home of Prime Minister Carlos Gomes in a coup just weeks before a runoff election. Gomes secured 49 percent of the vote during March presidential elections, which wasn't enough for a clear victory.
Gomes and acting President Raimundo Pereira are in custody.
Maria Luiza Ribeiro Viotti, the Brazilian envoy to the United Nations and chair of a peace-building commission for Guinea-Bissau, called for the release of political figures she said were illegally detained.
"The first step to further national reconciliation in Guinea-Bissau should be the respect of the rule of law and the restoration of constitutional order," she said in a statement.
None of the country's elected leaders has finished a term, succumbing to ailments, assassinations or military coups. A coup attempt was thwarted in December.
"The (Security) Council may wish to consider the imposition of targeted measures against those continuing to impede the return to constitutional order in the country," U.N. special envoy to Guinea-Bissau Joseph Mutaboda said in a statement.