UN human rights chief congratulates Senegal for its peaceful 25 March presidential run-off on Wednesday, noting, "Mali also had a good record of democratic elections over the past two decades, and I hope it gets back on that track as soon as possible."
Military rebels staged a coup on 22 March, toppling Mali President Amadou Toumani Toure just weeks ahead of the first round of a presidential elections scheduled for 29 April.
The coup leaders cancelled the vote and has not yet set a new date for elections.
"Unconstitutional changes of government, accompanied by violence, can have a devastating impact on the human rights situation," Pillay warned.
Turning to Guinea Bissau where the first round of a presidential election was held in tense but violence-free conditions on 18 March, Pillay said: "It is vital that the second round is also free and fair and violence-free."
"I call on all those taking part, especially the candidates and their supporters, to refrain from making provocative and inflammatory statements," she said.
"I also call on all security forces to act in conformity with the law throughout this process."
Guinea Bissau's presidential poll has been marred by allegations of fraud, with ex-president Kumba Yala leading calls by five opposition candidates to have the election annulled.
Yala, who came in second in the first round, is to face former prime minister Carlos Gomes in the run-off on 22 April.