"Acts of terrorism and an aggressive war by extremists led us to this decision," he said.
He said, without elaborating, that there was a plan aimed at "burning Egypt." State media has frequently accused Morsi's Muslim Brotherhood group and their supporters of carrying out acts of terrorism and attacking police stations, churches and government buildings.
Morsi's backers say the new leaders are relying on security forces and a corrupt system to go after the group to avoid finding a political solution or compromises to the crisis.
Mansour said that his government would not hold reconciliation talks with any individuals who have incited or taken part in acts of violence.
He said the fate of the Brotherhood is now in the hands of the judiciary, which is reviewing a case calling for the group's dissolution on the grounds it allegedly operated outside the boundaries of the law. The country's interim prime minister recently said the Brotherhood should be allowed to have a political party and be monitored rather than be forced underground as it had been for more than 80 years.
In the past several weeks, many leaders and members of the Brotherhood have been detained and face prosecution on charges ranging from inciting violence to possession of weapons and murder. Morsi himself has been held in an undisclosed location since his July 3 ouster. He has been referred to trial for inciting the murder of his opponents last year, though no date has been set.
Despite the fierce crackdown against Morsi's backers and those critical of his ouster, thousands protested across the country Tuesday in scattered marches and raised the ex-president's picture.
Meanwhile, a court on Tuesday ordered Al-Jazeera's local affiliate and three other stations to stop broadcasting. The case against Al-Jazeera Mubasher Misr has been mounting for weeks. The station has aired videos of wanted Brotherhood figures calling for more protests and focused extensive coverage on the group's rallies.
The court said in its ruling that the stations "hurt national security," as well as "broadcast lies to the Egyptian people, defamed the armed forces, violated the professional code of conduct, and incited foreign countries against Egypt," according to the state news agency MENA.
The Committee to Protect Journalists said authorities are trying to undermine coverage of anti-government activities by harassing and detaining journalists from media critical of the military-led government.
In another legal move, a military tribunal issued the first verdicts against backers of Morsi for riots in the city of Suez that were part of a nationwide wave of violence sparked when security forces cracked down on pro-Morsi camps in Cairo, killing hundreds.
Military officials said one person received a life sentence, three people were sentenced to 15 years, one person to 10 years and 47 to five years in prison. Twelve were acquitted. The officials spoke on condition of anonymity because he was not authorized to speak to the press.
Malek Adly, a rights lawyer who is following the security sweep against the Brotherhood, noted that it was Morsi and his supporters who backed an article allowing military trials of civilians in the constitution drafted and approved during his year in office.
"Now, they are the first to be tried according to it," he said.
Violence has also been on the rise in the Sinai Peninsula where the military has stepped up its campaign against militants. Helicopter gunships rocketed houses and cars in several villages there on Tuesday, targeting what the state news agency MENA said were hideouts of militants. At least eight suspected militants were killed and 15 wounded, it said.
The sudden ouster of Morsi after several days of huge protests has also rattled U.S.-Egypt relations. The decision by Egypt's new leaders to authorize force to clear out two large Brotherhood-led protest encampments in the capital further strained relations, prompting President Barack Obama to call for a review of relations.
"We wait to see the results of the review of relations that President Obama called for," Mansour said.
He spoke sharply about Turkish leaders, who have strongly criticized Morsi's removal from power. Ties have been strained and both countries have pulled out their ambassadors.
"We would have hoped that the Turkish government sees its real interests are with Egypt and its people and not with the leaders of a certain group that made ties with Turkish leaders based on personal interests based on economic incentives," Mansour said.
The turmoil and violence has scared away tourists and driven away foreign investors. Mansour said he would not paint a "rosy picture" of the situation and instead read off a list of grim figures that pointed to the many obstacles Egypt faces in its recovery.
Mansour said unemployment was at 13 percent and that foreign investment in Egypt has sunk to just $2 billion from $13 billion five years ago. He said Egypt's foreign debt is around $38 billion and its budget deficit at $26.5 billion. He said the country's foreign reserves are half of what they were before 2011, when the country erupted in protest. He said that tourism, which pumps some $15 billion into Egypt's economy, needs to be revived.
"I hope that Egypt's image abroad improves," he said while defending Morsi's ouster as a "revolution."
Although some U.S. senators and European leaders have called it a coup, Mansour insisted it was the will of people who voted for Morsi to remove him from power for failing to govern democratically.
"This is real democracy," he said.
