Schraner Burgener said that in conversations with Myanmar's deputy military chief Soe Win, she had warned him that the military was likely to face strong measures from some countries and isolation in retaliation for the coup.
The U.S. called the images appalling, the United Nations human rights chief said it was time to "end the military's stranglehold over democracy in Myanmar", and the world body's independent expert on human rights in the country, Tom Andrews, urged Security Council members to watch the videos.
Days later, a civil disobedience movement began, with many people refusing to return to work and some taking to the streets to protest. The report showed that despite the order, Myanmar security forces continued to murder, torture, and fire indiscriminately on Rohingya civilians, while continuing to deny them equal access to citizenship rights.
"I'm horrified by the escalation of violence in Myanmar and the killing of pro-democracy protesters", he said.
Witnesses said at least eight people were killed in the main city Yangon.
"The answer was: "We are used to sanctions, and we survived", she told reporters in NY.
"I heard so much continuous firing".
US State Department Spokesperson Ned Price says the U.S.is "saddened" by the latest brutal crackdown in Myanmar and is calling on China to join in helping to stop the violence.
The United States has conveyed to China that it is looking for Beijing to play a constructive role in Myanmar, the spokesman said.
The administration of President Joe Biden has already imposed sanctions such as asset freezes on 12 senior officials of Myanmar's military, including their top leader, and three related entities.
The US has tightened export controls on Myanmar, putting the country in the same category as adversaries Russian Federation and China, and limited the transfer of any equipment with military uses.
Two deaths each were reported in Salin, a town in Magwe region, and in Mandalay, the country's second-biggest city.
Save the Children said in a statement four children were among the dead, including a 14-year-old boy who Radio Free Asia reported was shot dead by a soldier on a passing convoy of military trucks.
Security forces breaking up protests in Yangon detained about 300 protesters, Myanmar Now news agency reported. Video posted on social media showed lines of young men with their hands on their heads.
Crowds gathered in Mandalay on Thursday for the funeral of a 19-year-old woman who was shot dead during protests on Wednesday. Reuters was unable to verify the video independently.
Foreign ministers of the Association of Southeast Asian Nations held an informal meeting with a representative of the junta on Tuesday via videoconference and pressed the junta to release Suu Kyi and refrain from using lethal force against the protesters.
"We must denounce the actions by the military", she said. When she also warned that Myanmar would become isolated, Schraner Burgener said, "the answer was, 'We have to learn to walk with only a few friends'".
The Myanmar military claimed that its action came after reports of fraud in the November 8 election were ignored. The election commission said the vote was fair, but the military has used media to make its case and justify the takeover.
Military Chief Min Aung Hlaing declared a one-year state of emergency and said new elections will be held to bring about a "true and disciplined democracy".
The global response to the coup has so far been fitful, but a flood of videos shared online showing security forces brutally targeting protesters and other civilians led to calls for more action.