The attack on Melania Geymonat, 28, and her girlfriend Chris happened on the top of a double-decker London night bus as they were travelling from West Hampstead to Camden Town.
Scotland Yard said four men aged between 15 and 18 were arrested on suspicion of robbery and aggravated GBH on Friday and have been taken to separate London police stations for questioning.
A group of young men allegedly began harassing the two women when they discovered they were a couple, asking them to kiss while making sexual gestures.
Miss Geymonat said in a Facebook post that the gang behaved like "hooligans", throwing money at the couple before punching them in an attack which left them covered in blood.
Both women were taken to hospital for treatment to facial injuries after the incident in the early hours of May 30.
Police continue to appeal for witnesses and information after the alleged assault, which happened on the N31 bus, and continue to trace other individuals suspected to have been involved.
Prime Minister Theresa May and Labour leader Jeremy Corbyn both condemned the attack.
Mrs May said: "This was a sickening attack and my thoughts are with the couple affected.
"Nobody should ever have to hide who they are or who they love and we must work together to eradicate unacceptable violence towards the LGBT community."
And Mr Corbyn said: "We must not, and will not, accept this homophobic and misogynist violence in our society.
"Solidarity to Melania and Chris, and to all in the LGBT+ community for everything they endure for simply being who they are."
Detective Superintendent Andy Cox said: "This was a disgusting attack on two women who appear to have been picked out and targeted by a group of youths.
"CCTV footage from the attack is being reviewed by detectives. We continue to appeal for information from the public, particularly those who were present on the bus before or after the attack to come forward and tell police what they saw.
"Lots of people will understandably be outraged by this attack. Our efforts to trace all the suspects involved and bring them in for questioning will be relentless.
"Attacks of this nature on London buses are rare. I would like to reassure those heading out over the weekend that extra uniformed and plain clothes Safer Transport officers will be out on patrol working to keep them safe and prevent crime."