"Were it not for the fence, we would be faced with severe attacks by Sinai terrorists, and something much worse - a flood of illegal migrants from Africa," Netanyahu's office quoted him as saying in a development conference in the southern Israeli town of Dimona.
There are currently some 42,000 African migrants in Israel.
Israel is set to expel nearly tens of thousands of Africans in a migrant relocation plan that has been described by the UN as "incoherent and unsafe".
The plan, originally introduced in November, will see the 38,000 African migrants, mainly Eritrean and Sudanese, who have entered the country illegally, leave by the end of March.
African migrants have been promised a plane ticket and $3,500, however, those that miss the deadline and refuse to leave, will face arrest.
The Israeli government insists that all but a few are economic migrants, but critics have slammed the plan, saying they are mostly bona fide refugees fleeing persecution and that kicking them out would endanger their lives.
The migrants are thought to have entered Israel in 2007 through what was then a porous border with Egypt's lawless Sinai region. The frontier with Israel's Negev Desert has since been given a 200-kilometre high-tech fence, preventing the influx of illegal migrants.
Netanyahu said a tide of non-Jewish immigration would threaten the very fabric of Israel.
"We are talking about a Jewish and democratic state, but how could we assure a Jewish and democratic state with 50,000 and then 100,000 and 150,000 migrants a year," Netanyahu said.
"After a million, 1.5 million, we might as well shut up shop," he added. "We did not close down, we built a fence."
Israel said it will pay almost $9,000 dollars to citizens who help in the forced expulsion of asylum seekers.
The job entails the "enforcement of laws against asylum seekers and their employers. Their job would be to find them, record their stories and investigate the employers as well".
"Experience in combat or security is a plus," the statement added.
Racism and remembrance
A sharp shift to the right in Israeli politics has given rise to an increasingly vocal push to isolate African asylum seekers and ultimately return them to their homelands. Darfur and Eritrea, being the majority, are both riddled by instability, long running conflicts and political oppression.
Between January 2016 to March 2017, a total of 311 citizens of Sudan and Eritrea were detained without trial.
Nationalist anti-immigration protests regularly turn violent with random beatings of Africans and the ransacking of their properties or shops.
Demonstrators have chanted slogans such as: "Stop talking, start expelling" and "Blacks out!", while other protesters have derided the "bleeding-heart leftists" working to help them.
Netanyahu noted that after building a fence on the Egyptian border and deporting some 20,000 African migrants through various deals, Israel has reached the third stage of its efforts - "accelerated removal".
"This removal is taking place thanks to an international agreement I reached that enables us to remove the 40,000 infiltrators remaining, remove them without their consent," he told ministers.
Holocaust survivors however have appealed to Netanyahu to cancel his plan to forcefully expel tens of thousands of African migrants, citing their own experiences as outcasts.
"We, who know precisely what it's like to be refugees, to be homeless and bereft of a state that preserves and protects us from violence and suffering, cannot comprehend how a Jewish government can expel refugees and asylum seekers to a journey of suffering, torment and death," the 36 signatories wrote in an open letter.