Two actors were attacked on their way to a theatre performance in what was described as a "cowardly homophobic hate crime".
Lucy Jane Parkinson and Rebecca Banatvala were appearing in Rotterdam, which tells the story of a young gay woman, at Southampton's NST Campus.
The theatre company said they were left "hugely shaken" after an object was thrown at them on Saturday afternoon.
Hampshire police said it had received a report of homophobic abuse.
Two performances of the Olivier Award-winning play by Jon Brittain were cancelled as a result.
The London-based couple said they were walking to the theatre for the matinee performance on Saturday when Ms Parkinson was hit by an object - possibly "stones", according to police - apparently thrown from a passing car.
Ms Parkinson said as she kissed her partner, fellow actor Ms Banatvala, she was struck and knocked to the ground, leaving her with slight injuries.
She said they heard "young boys laughing" as the car drove off.
Ms Parkinson said: "We're just two people looking for happiness like everybody else.
'Shocked and angry'
"I don't really understand why we're met with aggression from strangers."
Ms Banatvala said she was left "really shocked, upset and angry".
"It's made realise the importance of this play and stories like it," she said. "It needs to be seen as something that is normal and regular and isn't something to be feared or attacked."
A statement from the show's production company, Hartshorn-Hook, said the pair were left "hugely shaken from this cowardly, homophobic hate crime".
Announcing the cancellation of Saturday's two performances, it added: "We are devastated that this kind of behaviour is still so prevalent, a fact which reinforces the importance of this play's message.
"We are doing all we can to support the team and thank our audiences and colleagues for their support."
NST director Sam Hodges tweeted: "I am extremely sad that this sort of appalling behaviour is still happening anywhere, let alone in a city where we have worked so hard to promote a culture of tolerance, inclusivity and civic pride."
After initially requesting that the police did not take any further action, the couple have since made a report.
A Hampshire police spokeswoman said the matter is under investigation and appealed for witnesses.
"We have received a report from a third party relating to an incident which happened on Hill Lane, Southampton.
"It has been reported that homophobic abuse was shouted at two women, and stones thrown at them, by a the occupants of a passing car," she said.
The incident comes a few days after it was revealed that two women were left covered in blood following a homophobic attack on a night bus in London.