The Polish government has come under international criticism in recent years for promoting "LGBT free zones" and fueling homophobic rhetoric.
Diplomats from 40 countries on Monday called for the protection of LGBTQ rights in Poland.
The ambassadors' letter was published on the occasion of the International Day Against Homophobia, Biphobia and Transphobia.
It was signed, among others, by the US ambassador in Warsaw, most of Poland's European Union partners, as well as representatives from the European Commission and the United Nations refugee agency (UNHCR).
"We express our support for the efforts to raise public awareness of issues affecting the lesbian, gay, bisexual, transgender and intersex (LGBTI) community and other communities in Poland facing similar challenges," the letter read.
"To shield communities in need of protection from verbal and physical abuse and hate speech, we need to jointly work on an environment of non-discrimination, tolerance and mutual acceptance," it said.
The rights of minorities have become a flashpoint in recent years in Poland, led by the conservative populist Law and Justice (PiS) party which campaigns against what it calls "LGBT ideology".
According to PiS party leader Jaroslaw Kaczynski, gay people pose a threat to the traditional family. President Andrzej Duda equated "LGBT ideology" with communism.
With support from the government, several regions have also declared themselves free from "LGBT ideology".
The Council of Europe said in December last year that Poland's record for LGBTQ rights was the worst in the EU, noting that leading politicians had made the situation even worse in recent years.
Tensions between Warsaw and Brussels have escalated in recent years over moves seen as undermining the independence of the judiciary, media freedom and the rights of women and LGBTQ people.
The EU adopted at the end of last year a new rule of law mechanism that ties respect for the EU's core democratic values with EU funding.
Yet the mechanism hasn't entered into force yet and the government is currently eying €36 billion of European funds aimed at mitigating the impact of the pandemic.