Afkham's remarks came after a military-installed court in the town of Minya, South of the Egyptian capital of Cairo, upheld on Saturday the death sentences issued for 183 Muslim Brotherhood members.
"This is a concerning trend and contradicts Egypt's rich civilization, history and culture which are imbued with tolerance and compromise," Afkham said on Sunday.
She noted that the achievement of Egypt’s revolution belongs to all the country’s people and its varied spectrum of political and social groups.
"At the current sensitive juncture, it is very important and effective to display national unity in Egypt on the basis of political will and the move towards establishing democracy," the Iranian foreign ministry spokeswoman said.
The Muslim Brotherhood members have been accused of involvement in the murder and attempted murder of policemen in Minya Province on August 14, 2013, the day police killed hundreds of Muslim Brotherhood supporters in clashes in Cairo.
In late April, an Egyptian court recommended the death sentence for the leader of the Muslim Brotherhood and 682 supporters, and handed down a final capital punishment ruling for 37 others.
Seeking the death penalty for Mohamed Badie, the Brotherhood's general guide, is certain to raise tension in Egypt, which has been gripped by turmoil since the army removed the Brotherhood from power last year, Reuters reported.
The 37 death sentences were part of a final judgment on 529 Muslim Brotherhood supporters who were sentenced to death last month. The remaining defendants were sentenced to life in jail.
Death sentence recommendations in the case involving Badie will be passed on to Egypt's Mufti, the highest religious authority. His opinion is not legally binding and can be ignored by the court.
The biggest trials in Egypt's modern history have reinforced fears among human rights groups that the military-backed government and anti-Islamist judges are bent on crushing dissent.
The authorities have branded the Brotherhood a terrorist group, an allegation it denies.
In April, Afkham voiced Tehran's deep concern about political tensions in Egypt, specially the verdicts issued by the country's court against the Muslim Brotherhood members.
“The issuance of these rulings can have numerous social and political repercussions and encourage the enemies of Egypt to further aggravate the ongoing situation,” Afkham said at her weekly press conference in Tehran.
“The Islamic Republic of Iran closely monitors the country’s (Egypt) developments … and respects the great revolution of this country as well as (the need for) the maintenance and realization of its achievements,” she added.
Afkham also stressed the importance of establishing national unity among civil institutions and movements to meet the Egyptian people’s demands and preserve the country’s historical and civil glory.
Afkham emphasized that the court verdicts run counter to the “principle of tolerance”.
