Gambari said on Friday: "Of great concern to the UN and the international community are the continuing and disturbing reports of abuses being committed by security and non-uniformed elements."
'Arrests and disappearances'
He said abuses tookplace "particularly at night during curfew, including raids on private homes, beatings, arbitrary arrests, and disappearances."
Myanmar's state-run media has admitted that 10 people died in the crackdown but foreign governments and dissident groups say they believe the toll runs into the hundreds.
"Where are the peace and human rights defenders of the world [the super powers]? They haven't done enough in this case. Isn't there oil in Myanmar?"
Lost Soldier, Arusha, Tanzania
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Gambari also said that there were unconfirmed reports that the number of casualties was much higher than the number reported killed by the government.
"We cannot go back to the situation before the recent crisis," Gambari said, adding that the underlying socio-economic and political factors must be addressed.
The envoy is considering a return visit to Myanmar earlier than mid-November, as initially arranged. He said this would be useful "to keep the momentum" generated by his four-day visit earlier this week.
"He is looking towards long-term solutions," Kristen Saloomey, Al Jazeera's correspondent at the United Nations in New York, said.
"His priority right now is encouraging dialogue between Aung San Suu Kyi and the military government. What he is trying to address is the underlying issues that led to the demonstrations."
'Abhorrent and unacceptable'
Gambari's comments came shortly after Ban Ki-moon, the UN secretary-general, spoke before the council, urging Myanmar's military rulers to "take bold actions towards democratisation and respect for human rights."
"I must reiterate that the use of force against peaceful demonstrators is abhorrent and unacceptable," he said.
Zalmay Khalilzad, the US ambassador to the UN, told the council: "If the Burmese government does not take appropriate steps... the United States is prepared to introduce a resolution in the Security Council imposing sanctions.
"We must all be prepared to consider measures such as arms embargoes."
In response, Kyaw Tint Swe, Myanmar's ambassador to the UN told the Security Council that no action was warranted against his government.
The ambassador urged the UN not to take steps that would harm the "good offices" role of the world body to defuse the situation in Myanmar.
Wang Guangya, China's UN ambassador to the UN, reiterated Beijing's view that Myanmar posed no threat to international peace and security, a condition for Security Council action.
China neighbours Myanmar and is one of the country's few allies and major trading partners.
The ambassador said pressure "will not help address the problem but might lead to mistrust and confrontation."
'No time for talk'
About one dozen monks from the All Burma Young Monks' Union watched the discussion from the front row of the security council visitors' gallery. But afterwards one of them said they were not happy because they wanted action rather than talk.
"Every single day they attack the monks and they kill people who are against them. Every single day, every single minute, every single hour, so there's no time for doing like this," Ashin Kay Matethara told the Associated Press.
"They [Myanmar's military] break up monasteries in Burma. They catch monks and they put them in jail. Maybe they die right away because they are beaten by knives. They even broke Buddha's statue."
The monks, along with supporters, have been holding daily demonstrations outside UN headquarters for the past week. Matethara said they would also demonstrate on Friday outside the Chinese Embassy.
Meanwhile, the party of Aung San Suu Kyi, the detained pro-democracy leader, has dismissed the Myanmar government's conditions for talks as surreal.
Nyan Win, spokesman for the Nobel peace laureate's National League for Democracy, said: "They are asking her to confess to offences that she has not committed."
On Thursday, General Than Shwe, who caused international outrage by sending in soldiers to crush peaceful monk-led demonstrations, had asked Suu Kyi to abandon "confrontation," and give up "obstructive measures" and support for sanctions and "utter devastation".
Source: Al Jazeera and agencies