According to the spokesperson, members of the 71 official government delegation were among those who were intimidated ahead of UN's vote.
It is reported that Geneva's Sri Lankan ambassador also recieved anonymous threat.
Meanwhile, India was heavily criticised by Sri Lankan dailies after it voted against Sri Lanka in the US moved resolution.
"Only one vote majority for resolution; 24 say 'yes', 23 decline to support," said the Daily News.
The Daily also critised India calling it "misconceived, unwarranted and ill-timed resolution".
"Those who live in glass houses are best advised to exercise caution before throwing stones," it said.
"Geneva: Lanka fails to beat the odds," read the headline at infolanka.com.
"It is a matter of great satisfaction to us that 15 countries voted with Sri Lanka, despite the intensity of pressure, in a variety of forms, exerted on them all," said news.lk.
"India succumbed to US pressure to vote for the resolution, key Asian countries, including those representing SAARC and two UN Security Council members voted against it," it said.