A joint statement from the embassies of 29 mostly Western countries in Bucharest, as well as the European Commission, urged Romania on Friday to protect its LGBTI citizens from discrimination.
"On the occasion of the International Day Against Homophobia, Transphobia and Biphobia, we express our solidarity with all marginalised groups in Romania, regardless of their sexual orientation, gender identity and sexual characteristics," said the statement, a copy of which was sent to AFP by the British Embassy.
"LGBTI persons continue to face discrimination... We believe that only when diversity is appreciated and supported can a country achieve its full potential,, the statement added.
Romania ranks 25th out of the 28 EU countries for progress in eliminating discriminatory legislation and hate speech against LGBTI people, according to the ILGA-Europe network of rights groups.
Only Bulgaria, Poland and Latvia have a worse raking in the European Union.
Romania's left-wing government was accused of fuelling hate earlier this year after organising a referendum aimed at changing the current definition of marriage as between "spouses" to explicitly being between a man and a woman.
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Although gay marriage is not legal in Romania, the proposal was seen as an attempt to block it ever being approved.
Despite a large majority of those voting approving the change, the referendum was declared invalid due to insufficient turnout.
The 2019 Bucharest Pride March will take place on June 22.
Last year, a record number of more 3,000 people participated and marched through the city centre.
The statement from the embassies stressed that "we support all the lawful and peaceful manifestations to enhance the importance of the International Day of Homophobia, Transphobia and Biphobia in Romania".