Speaking to Swedish Radio's Sports department, Green Tregaro said she painted her nails as a nice gesture.
"To me, love for another person is the most beautiful thing in the world, and that's what I want to show, no matter the gender or whatever," she said.
"For me sport is about respect and unity, so it felt like the perfect opportunity to show what I think."
Green Tregaro revealed her plans to compete in Moscow with the rainbow nails on Wednesday night via social media, adding the hashtag #pride. Her initiative received a good response, she said. Her decision also inspired sprinter Moa Hjelmer to paint her nails.
Hjelmer told Swedish Radio: "You can call it a silent protest against the anti-gay laws that have been introduced here in Russia. It doesn't feel very good. We can't choose where the championships are being held, but it is sad that they have these attitudes. It should be self-evident that everyone should have the same rights."
Meanwhile, former Swedish high jumper Kajsa Bergqvist, one of Sweden's biggest track and field stars over the past few decades says she will give Russian President Putin a piece of her mind if she runs into him in the VIP section of the stadium.
Speaking to tabloid Expressen, Bergqvist said: "You get sad and you get angry. When you face travelling to a country where you could go to prison for spreading 'gay propaganda'. 'Gay propaganda' - I don't even know what that is," she said
"I think the propaganda put forward by the Russian authorities is disgusting," she added.
The Swedish athletes' actions got support from among others British actor and writer Stephen Fry.
However, Russian pole vault gold medallist Yelena Isinbayeva has criticised the Swedish actions. At a press conference, she said: "It's unrespectful to our country, it's unrespectful to our citizens. Because we are Russians, maybe we are different from European people, maybe we are different to people from other lands, but we have our laws that everyone has to respect."
Isinbayeva added that she fully supports the new law. "If we will allow to promote, do all this stuff on the streets we are very afraid about our nation. We consider ourselves normal standard people, with boys with women, women with boys. Everything was fine, this comes from history. We've never had these problems in Russia and we don't want to have it in the future," she added.
After Isinbayeva's comments a string of Swedish sports stars voiced their support for Green Tregaro and Hjelmer.
Kajsa Bergqvist said Isinbajeva's comments will throw a dark shadow over her career and athlete Patrik Sjöberg told Expressen: "If she (Isinbajeva) stands for these opinions, then that's like the stone age. It's good of Emma to take this kind of initiative. I don't know what Isinbajeva stands to gain from saying such things, but I guess they have different views in the East. They probably have not come as far as other countries," said Sjöberg.
Former high-jump champion Stefan Holm, who is now an expert commentator for Sweden's TV4, said:
"She is probably pretty good friends with many people in high positions in Russian sports and in politics. The question is whether she dares say anything different even if she really had a different opinion. I hope she doesn't truly feel this way because that would actually be scary."
On social media, like Twitter and Instagram, Green Tregaro was cheered on by people from all over the world.
Green Tregaro qualified for the high jump final after clearing 1.92m in her first jump, and javelin thrower Kim Amb also made his final, but sprinter Moa Hjelmer failed to reach the semi-final of the 200m, coming sixth in her heat. Hjelmer had previously also been knocked out of the 400m competition.
Sweden's Abeba Aregawi won gold Thursday evening in the women's 1,500m final.
(With thanks to Swedish Radio's Sports Department.)