Motahari told on his website how surveillance equipment was discovered in an air conditioning duct on July 9.
His online comments were initially blocked after he posted them, but were able to be viewed again on Sunday.
Motahari said: “The chief of staff of my office outside parliament saw changes in the air conditioning duct. He opened the air vent and found a security camera and a listening device.
The images retrieved from the camera showed nine men installing equipment in the room, wrote Mr Motahari, who is being seen as leading candidate for minister of culture and Islamic guidance in the cabinet of incoming president Hassan Rowhani.
He added: “When such an event happens to a well-known member of Parliament, one can only imagine how much the ordinary people are being oppressed.”
On Sunday, several MPs also called for a public hearing to question intelligence minister Heydar Moslehi, who is closely aligned with Supreme Leader Ali Khamenei and the Revolutionary Guards.
MP Ahmad Tavakoli said in a speech: “We must seriously ask the Intelligence Ministry to make everything clear and show that the Islamic republic supports constructive criticism.”