Foreign Secretary Jeremy Hunt said Monday that Laleh Shahravesh "is getting the best possible service" from British diplomats.
The group Detained in Dubai says Shahravesh was arrested at Dubai Airport on March 10 as she arrived for her ex-husband's funeral. Authorities there had received a complaint about Facebook posts that she allegedly made in 2016 calling her ex's new wife a "horse."
The United Arab Emirates has strict laws about what can be posted online.
Detained in Dubai, which helps people who fall foul of the Gulf state's legal system, says Shahravesh faces a maximum sentence of two years in prison and a 50,000-pound ($65,000) fine.