Some wore a noose around their neck, others held candles and displayed rainbow flags.
They were protesting the Vatican's hostile stance towards the declaration, which is being presented by France on behalf of the EU.
Monsignor Celestino Migliore, the Holy See's permanent observer at the UN, said last week that the declaration could be used to force countries to recognise same-sex marriage.
"If adopted, they would create new and implacable discriminations," he said.
"For example, states which do not recognise same-sex unions as 'matrimony' will be pilloried and made an object of pressure."
More than 90 countries outlaw same-sex relations in all circumstances.
The maximum punishments range from a few years jail to life imprisonment.
In nine countries, or regions of countries, the mandatory punishment for homosexuality is death by execution.
There is no mention of same-sex marriage in the UN declaration.
Only a handful of countries recognise gay and lesbian marriages, among them Canada, Belgium and South Africa.
Aurelio Mancuso, national president of Italian gay rights group Arcigay, said the Vatican was wicked.
"What happened today is extremely important," he said after the protest.
"LGBT people have launched a global campaign in defence of life and dignity of thousands of lesbian, gay, bisexual, transgender citizens and the wickedness of Vatican politicians must not prevail over the human rights."
There were a series of other rallies across Italy - Acrigay said they hoped to start a constructive dialogue with the "community of believers who, as many polls confirm, disagree with the Holy See position."
The French initiative is backed by all EU nations along with Norway, Switzerland, Iceland, Ukraine, Andorra, Liechtenstein, Bosnia and Herzegovina, Croatia, Montenegro, Serbia, Ukraine, and the former Yugoslav Republic of Macedonia.
In the Americas the most notable absence is the United States.
Canada has signed up alongside Argentina, Brazil, Chile, Ecuador, Mexico and Uruguay.
Three African nations - Gabon, Cape Verde and Guinea-Bissau - are committed to the declaration alongside New Zealand, Israel, Armenia and Japan.
Louis Georges Tin, the founder of the Inernational Day Against Homophobia, is behind the universal decriminalisation declaration.
He met with Rama Yade, France's minister of human rights and foreign affairs, earlier this year.
In September she confirmed that she will appeal at the United Nations for the universal decriminalisation of homosexuality.
Until the end of 2008 France will speak for all EU member states at the UN General Assembly, as they hold the rotating Presidency of the European Union.
The French initiative on decrminalisation will take the form of a solemn declaration from UN states, rather than a vote in the UN on the matter.
France will submit a draft declaration at the UN General Assembly between December 15th and 20th. The British government already advocates universal decriminalisation.
Australian gay rights activist Rodney Croome is claiming the Australian government "intends to support" the declaration.
+++++++++++++++++++++++++++++++++++++++++++++++++++
Disclaimer
No responsibility or liability shall attach itself to either myself or to the blogspot ‘Clerical Whispers’ for any or all of the articles placed here.
The placing of an article hereupon does not necessarily imply that I agree or accept the contents of the article as being necessarily factual in theology, dogma or otherwise.
Sotto Voce
(Source: PNUK)