The Polish government responded to the letter saying that while they respected the human rights of LGBT people, marriage was between a man and a woman.
Ambassadors to Poland from some 50 countries and international organisations have expressed their support for the LGBT community in the country, citing a need to work for "non-discrimination, tolerance and mutual acceptance."
The appeal, made in an open letter published on Sunday, comes as an increasingly visible LGBT community in Poland has faced a backlash from the right-wing government, many local communities, and the Catholic church.
“Human rights are universal and everyone, including LGBTI persons, are entitled to their full enjoyment,” the letter said, using the acronym for lesbian, gay, bisexual, transgender and intersex people.
Some of Poland's leaders, including the president and lawmakers from the ruling party, have cast the movement for civil rights for LGBT people as a threat to traditional families. President Andrzej Duda won a second term this summer after calling LGBT rights an “ideology” more dangerous than communism.
Meanwhile, dozens of towns in conservative parts of eastern and southern Poland have passed resolutions over the past nearly two years declaring themselves to be free from “LGBT ideology” or expressing support for families described as centred on unions between a man and woman.
A Polish deputy foreign minister, Paweł Jabłoński, replied to the open letter by saying the Polish government fully agrees with its message and that “every human being enjoys an equal level of protection under Polish law,” but he added that "according to the Polish Constitution, marriage is a union of a woman and a man.”
Jabłoński said the local resolutions do not amount to discrimination but are “a sign of respect for the rule of law, and for the values that Poles hold dear.”
The ambassadors' letter paid tribute to the work of the LGBT community in Poland as it seeks to raise awareness about the challenges its faces.
Many activists say their greatest priority now is to get legislation passed criminalising violence against people based on their sexual identity. The lack of such legislation has many ramifications, including the fact that attacks on LGBT people are not currently documented in police statistics.
The letter was signed by the ambassadors of the United States, many European countries, including Germany, Ukraine and the United Kingdom, as well as further off nations like Japan and Australia.
It was also signed by representatives in Poland of the United Nations, the European Union, the Organization for Security and Cooperation in Europe and the Community of Democracies, which is based in Warsaw.