Speaking at the weekly cabinet meeting, Netanyahu also announced the start of construction of a fence along Israel's border with Jordan, according to his office.
"We will not allow Israel to be submerged by a wave of illegal migrants and terrorist activists," Netanyahu said.
"Israel is not indifferent to the human tragedy of Syrian and African refugees... But Israel is a small country -- very small -- without demographic or geographic depth. That is why we must control our borders."
Palestinian president Mahmud Abbas also called for Israel to allow Palestinians from refugee camps in Syria to travel to the Palestinian territories, whose external borders are controlled by the Jewish state.
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There is already hostility in Israel toward asylum-seekers from Africa and a concerted government effort to repatriate them.
Rights groups say thousands of African asylum seekers have been coerced into "voluntary" departures.
Official figures show 45,000 illegal immigrants are in Israel, almost all from Eritrea and Sudan. Most of those not in detention live in poor areas of southern Tel Aviv, where there have been several protests against them.