ILGA-Europe is active in 45 European countries, representing 400 organisations fighting for the human rights of lesbian, gay, bisexual, trans and intersex people.
On December 1, Croatian citizens will take part in a referendum asking if marriage should be defined in the Constitution as a union between a man and woman.
"ILGA-Europe is disappointed that Croatia, a new member of the European Union, marks its entry into a Union based on the principles of equality, dignity and respect for human rights for all with a referendum which has no other aim but to restrict the rights of some citizens of Croatia," the statement said, calling "on all citizens of Croatia who value freedom, respect and human rights to vote no at this referendum."
"We appeal to political leaders, opinion makers and prominent personalities in Croatia to publicly voice their opposition to this restrictive and discriminatory constitutional amendment... It is time for Croatia to decide if it wants to build a democratic country where every person is respected and a society where happiness of all people matters, or a country which wants to anchor discrimination in its main law," ILGA-Europe said.
"Marriage equality and recognition of same-sex unions is not a threat or danger to anyone. It is simply another step towards the elimination of oppression and discrimination. Research from countries where same-sex unions are legally recognised and protection from discrimination exist, show a much higher level of happiness and content compared to those countries where inequality and discrimination still exist."
It added that the "number of countries that legally recognise same-sex unions is growing: 21 out of 49 European countries now do so."