The country's envoy to the UN blamed Rohingya insurgents for the violence in Rakhine state, saying that Myanmar would never tolerate such atrocities.
Some 370,000 Rohingyas have crossed the border to Bangladesh since the situation escalated last month.
On Monday, the UN High Commissioner for Human Rights, Zeid Raad Al Hussein, urged Myanmar to end the "cruel military operation", saying that it seemed "a textbook example of ethnic cleansing".
The following day Htin Lynn, Myanmar’s ambassador to the United Nations, said those allegations were unhelpful and wrong.
"The terms crimes against humanity and ethnic cleansing carry very serious connotations. They can only be used in the most responsible manner and they can only be founded on legal and judicial determinations," he told the UN Human Rights Council in Geneva.
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"Democratic Myanmar shall never tolerate such atrocities. I would like to place on record Myanmar's strong objection to the use of such terms by the high commissioner."
Bangladeshi sources say Myanmar's army recently planted new mines, an allegation denied by Myanmar officials.
Meanwhile, Bangladesh has urged Myanmar to take back hundreds of thousands of Rohingyas who have fled the violence.
The country is already home to hundreds of thousands of Rohingyas who have fled previous outbreaks of violence in Myanmar.
Two official refugee camps are full and aid agencies say the new arrivals desperately need food, shelter and medical help.
"My personal message is very clear, Myanmar should consider this situation with the eyes of humanity," Bangladesh's Prime Minister Sheikh Hasina told the BBC after visiting the Kutupalong camp.