Police took Blair, 54, into custody late on Sunday when the Delta Air Lines plane was parked at the gate at New York's John F Kennedy Airport, the Port Authority of New York and New Jersey said in a statement.
The Associated Press contacted the airline for comment on Monday afternoon.
Blair and one of the flight attendants were taken to hospital for evaluation, the Port Authority said.
The FBI, which is responsible for investigating all assaults aboard aircraft, declined to release details.
"Yesterday, we were informed by our partners at Port Authority Police Department of a potential assault aboard a flight that arrived into JFK. As per long-standing DOJ policy, we do not comment on ongoing investigations," said Sydney Kleinmann, a spokesperson for the FBI NY.
Messages seeking comment from the state and federal prosecutors' offices in New York, as well as Blair's publicist, were also sent on Monday.
In a statement to several media outlets, a Blair representative said she had a medical emergency that led to the alleged conduct.
Blair had major roles in films including 1999's Cruel Intentions, 2001's Legally Blonde and 2004's Hellboy.
In recent years, she has advocated for disability rights. She was diagnosed with multiple sclerosis in 2018.
In 2016, Blair apologised for making statements she regretted on a flight from Cancun to Los Angeles, saying that she mixed alcohol with medication, which made her black out.
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