He accused the generals of killing thousands of their countrymen and women by refusing foreign relief aid, but said the US will not force assistance on Myanmar.
"We have reached out, frankly, to Myanmar multiple times during this crisis in very direct ways," Gates said.
Growing displeasure with the Myanmar government has permeated the Singapore gathering, coming up in nearly all conversations between leaders from around the world.
"It's not been us that have been deaf and dumb in response to the pleas of the international community, but the government of Myanmar," Gates said.
"We have reached out, they have kept their hands in their pockets."
Slow response
Gates said the Myanmar government's slow response to Nargis's aftermath has cost "tens of thousands of lives".
He said US ships and aircraft could have swiftly brought much-needed relief to Myanmar.
"Our ships and aircraft awaited country approval so they could act promptly to save thousands of lives, approval of the kind granted by Indonesia immediately after the 2004 tsunami and by Bangladesh after a fierce cyclone just last November," Gates said.
"With Burma, the situation has been very different, at a cost of tens of thousands of lives."
Gates further said the US will not bring in supplies by force without the permission of the government, and will continue to "respect the sovereignty" of Myanmar.
US, British and French navy ships off the coast of Myanmar are poised to leave because they have been blocked from delivering assistance.
US officials have indicated they are about to withdraw the US navy ships within days, since it does not appear the Myanmar government will change its mind and allow them to unload supplies.