Iran opposition leader Mehdi Karroubi's car has been fired on in the northern city of Qazvin.
He was in the city for a religious ceremony. Mr Karroubi's website reports he was in the car at the time, but was not hurt. As it was an armoured car, only the windows were damaged.
The incident happened shortly after he left a house that had been surrounded by what the site called a well-organised group throwing stones.
Mr Karroubi was a reformist candidate in June's election. Along with the main opposition candidate, Mir Hossein Mousavi, he has organised a series of mass protests since then.
The BBC reports they have grown into the biggest challenge to the government since the 1979 Islamic revolution.