Shirin Ebadi is the first Muslim woman to win the Nobel Peace Prize
The US has expressed grave concern over what it called the worsening human rights situation in Iran.
State Department Spokesman Louis Fintor said the US was monitoring Tehran's actions towards the Iranian human rights activist Shirin Ebadi.
Ms Ebadi has been ordered to appear in court in Tehran to answer unspecified questions, or risk arrest.
She has clashed several times with the Iranian authorities since winning the Nobel peace prize in 2003.
On Thursday, Ms Ebadi told the BBC the judicial order was unlawful because it failed to spell out why she must go to the court.
The 57-year-old Ms Ebadi's defence of dissidents has brought her into frequent confrontation with Iran's theocratic authorities.
She recently called for the country's Islamic penal system to be reformed to safeguard human rights.
First woman judge
Ms Ebadi told the BBC she has not yet decided whether or not to respond to the court order, but will reach a decision by Saturday.
"The court order is against Iranian law," she said. "It should clarify why they are calling me and in relation to what case."
Since winning the Nobel Prize, Ms Ebadi has complained of increased threats against her and has been placed under police protection.
Ms Ebadi came to prominence when she was appointed Iran's first woman judge. That distinction was removed after the revolution.
In 2000, she was accused of distributing the videotaped confession of a hardliner who claimed that prominent conservative leaders were instigating physical attacks on pro-reform figures.
She received a suspended jail sentence and a professional ban for this. Recently, she has represented the family of Zahra Kazemi, a Canadian-Iranian photographer murdered in custody in 2003.