The ads, made by young French film director Francois Message and partly funded by the French embassy, show various homosexuals talking on camera about living their sexual orientation in the country.
"I don't like that I can't show my partner to my colleagues. I am lesbian and I support Baltic pride", said one, a 59-year-old who gave only her first name as Irena, speaking for an ad filmed in the Lithuanian capital Vilnius.
"The problem is the lack of knowledge. When you know LGBT (lesbian, gay, bisexual, transsexual) people, you realize it's fine, it's the same. I hope that these videos help to understand that for people who don't know or are afraid", Message, 26, told AFP.
The ads promoting the gay march will be shown nationwide in July, weeks before the homosexual rights campaigners will hold their second rally in the EU country.
An opinion poll released in March showed 62 percent of Lithuanians are opposed to the gay march.
But Vladimiras Simonko, a leading Lithuanian gay rights activist, said opposition has dropped since 2010 when police used tear gas to disperse hundreds of protesters.
Simonko praised the support from France, which is poised to adopt gay marriage law after heated debates and protests.
Same-sex relations were decriminalised in Lithuania in 1993, three years after the country declared independence from the crumbling Soviet Union, which had banned homosexuality.
Lithuania, where 77 percent of the three-million-strong population is Roman Catholic, joined the European Union in 2004.