The main pro-Morsi alliance has criticised Saudi Arabia for backing the "coup" in Egypt and for designating the Muslim Brotherhood a terrorist organisation.
"Saudi Arabia will remain a compass for all Muslims and an important support for the Arab and Islamic nation," the National Alliance to Support Legitimacy, led by the Brotherhood, said in a statement on Monday.
"Accordingly the alliance is surprised by [the kingdom's] continuing support for the coup [in Egypt]. This support is financial, political and moral. It has also criminalised opposition to the unjust coup."
Saudi Arabia strongly backed the ouster of Islamist president Mohamed Morsi in July 2013, and on Friday it designated his Muslim Brotherhood group a terrorist organisation.
The decision follows an unprecedented diplomatic act on Thursday when Saudi Arabia, Bahrain and the UAE withdrew their ambassadors from Qatar, over the latter's pro-Brotherhood foreign policy.
The statement further called on the kingdom to rethink its position and "take the side of Egyptians who are defending their freedom."
Morsi was ousted by the army on 3 July amid mass protests against his rule. Since then, thousands of Brotherhood members and supporters have been detained and hundreds killed in confrontations with security forces.
Islamist militants have stepped up their attacks against the security forces, killing dozens of police and army personnel.
Last month, a bomb hit a tourist bus in South Sinai, killing four. It was the first attack against civilians since the Morsi's ouster.
Egyptian authorities have blamed the Brotherhood for the violence, but the group has repeatedly denied involvement.
Egypt designated the Brotherhood a terrorist organisation in December 2013.