"No matter how strong the alliance between Israel and the Egyptian regime is, the Israeli occupation will remain the real enemy of the people in the region," Hamas spokesman Sami Abu Zuhri said in a statement.
On Saturday, Israeli politician Amos Yadlin of the centrist Zionist Union – an alliance between Israel's Labor and Hatnuah parties – described the Egyptian court verdict as "significant," according to Israeli radio.
"Israel needs to work with Egypt on several fronts to form a regional alliance against extremist elements," Yadlin was quoted as saying.
A Cairo court on Saturday designated Hamas as a "terrorist" group over claims that the group had carried out terrorist attacks in Egypt through tunnels linking the Sinai Peninsula to the Gaza Strip.
In March 2014, the same court outlawed Hamas' activities in Egypt and confiscated its offices.
The court had said that the ban would be temporary until another court – which is trying ousted President Mohamed Morsi for alleged "collaboration" with Hamas to carry out "hostile" acts in Egypt – delivers its final verdict.
Last month, another Egyptian court declared the Ezzedine al-Qassam Brigades, the military wing of Hamas, a terrorist organization.
A number of Hamas members have been among the defendants in two trials that Morsi – a Muslim Brotherhood leader – currently faces for alleged espionage and jailbreak.
Egypt's media has blamed Hamas, an ideological offshoot of the Brotherhood, for a series of deadly attacks on security forces since Morsi's ouster. Hamas has consistently denied the allegations.