A court in Bahrain on Monday fined Zainab al-Khawaja, the daughter of a prominent opposition activist, for insulting a government employee.
Her lawyer said she was still detained pending trial in a different case.
Bahrain, a U.S. ally that hosts Washington's Fifth Fleet, has been in turmoil since a democracy protest movement led by its majority Shi'ites erupted last year after revolts in Egypt and Tunisia.
Its Sunni Muslim rulers have rejected opposition calls for an elected government and protests and clashes with police continue weekly.
Khawaja, daughter of jailed uprising leader Abdulhadi al-Khawaja who has been on hunger strike for more than three months, was arrested a month ago for trying to stage a protest in the capital Manama during Bahrain's Formula One Grand Prix.
``She was fined 200 dinars (530 dollars) for insulting a public servant,'' lawyer Mohammed al-Jishi told Reuters, adding the court will try her for attempting to stage a protest on May 24.
``She could be fined again or sentenced to prison," he said.
The authorities have dubbed the opposition Iranian lackeys because most of them are Shi'ites, as in Iran.
They have vowed to get tough on security as talks with the opposition stalled.
The desire to contain Shi'ite dissent in Bahrain and counter Iran's sway drove efforts to unify the six members of the Gulf Cooperation Council (GCC), which stumbled at a meeting of their leaders last week.