"This issue [reconciliation] is no longer on the table," Mansour said. "It is no longer acceptable at the public level after they [the Brotherhood] committed murder and sabotage crimes," he added in an interview with the Arabic language daily Al-Ahram published on Monday.
Egypt designated the Muslim Brotherhood as a "terrorist" movement in late 2013 immediately after the bombing of a security headquarters in the Nile Delta city of Mansoura.
The Brotherhood denied any links with the attack and even condemned it.
In his interview with Al-Ahram, Mansour called on Egyptians to work hard, saying work was the only way for this country to get over its current hardships.
"Citizens yearn to retain their stolen rights, but there is no magical wand that can achieve in a few months things that were not achieved in decades," the interim leader said.
He said Egypt's next president must have backing from the public in order to be able to take "tough" decisions for the best interest of Egypt.
Speaking about the country's foreign policy, Mansour asserted that Egypt is keen on retaining its position as a major powerhouse in the Middle East.
He also underlined the importance of relations between his country and the United States, saying Egypt will be keen on preserving these relations as long as the US does the same.
"The Egyptian people sent a message to the US after June 30 to the effect that it will not accept any foreign interference in the internal affairs of their country," Mansour said.
He also pointed out that Egypt and Russia will build on a good heritage of relations between them to perk up their economic and military ties in the future.
He, however, said this does not mean that Egyptians view Russia as an "alternative" to any other country.