Dozens of protesters attempted to storm the residence of the Iranian chargé d'affaires in Cairo on Friday.
The protesters, mostly Salafists, threw stones at the building and daubed offensive slogans on the outer wall.
They chanted against Iran, Shias and the Muslim Brotherhood and in support of the Syrian opposition.
"Let all the Muslim Brothers hear, we will not accept relations between Egypt and Iran," the protesters chanted. "Iranian ambassador, Egypt will not be Shia, Egypt is a Sunni country" and "Egypt and Syria are one hand."
The protesters carried banners saying "No to Shias in Egypt."
A number of journalists and photographers were assaulted during the protest.
Security forces dispersed the protesters with tear gas after a man tried to hang the Syrian independence flag on the gate of the residence.
"There were around 40 to 50 protesters in front of the residence. They were mostly Syrians from the opposition and they had the Syrian opposition flag," Mogabati Amani, Iranian charge d' affaires in Cairo told Ahram Online.
"These people are dangerous for Egyptian security because they are serving foreign interests," he said. "We know very well that the enemies of Egyptian-Iranian relations want to harm Egypt."
Amani said talks were underway with the foreign ministry to ensure such "actions will not be repeated again."
"Such actions could be harmful to the relations between the two countries, " stressed Amani.
Eyewitnesses said most of the protesters were Egyptian Salafists.
Salafists have been holding lectures across the country in recent weeks to warn against the spread Iranian Shiism to Egypt.
Tourism between Iran and Egypt has recently resumed for the first time in three decades.