An attacker with a penknife wounded Saturday a representative of the Rebel campaign in Qalyubiya governorate, some 40 kilometres from the capital Cairo.
Mohamed Gabri, 23, sustained injuries to his face and hand and was hospitalised before a complaint was filed with the police.
Gabri said he was distributing forms for the Rebel campaign, a signature drive that aims at collecting 15 million endorsements for "withdrawing confidence" from President Mohamed Morsi.
Gabri said the perpetrator was incited by the Muslim Brotherhood, the group from which Morsi hails from.
The Rebel campaign has called for mass protest at the presidential palace in Cairo on 30 June, with Islamist figures planning to stage counter-rallies that many expect will result in clashes.