JERUSALEM —Prime Minister Benjamin Netanyahu on Sunday criticized the presence of Palestinian flags at a protest against a contentious new law defining the country as a Jewish state.

Netanyahu told the Cabinet on Sunday that Palestinian flags ‘‘flying in the heart of Tel Aviv’’ were ‘‘conclusive evidence’’ that many protesters oppose Israel’s existence, and prove the law is necessary.

Tens of thousands rallied in Tel Aviv on Saturday against the law. Some Arab protesters waved Palestinian flags and others held signs reading ‘‘equality.’’

It was the second major protest against the law in recent weeks.Thousands of Druze, also members of the Arab minority, packed the same city square last week.

Supporters of the law say it enshrines the country’s existing character as a Jewish state. But critics say it undermines Israeli democracy and sidelines the country’s non-Jewish minorities. Approximately 20 percent of Israelis are Arab.

Israel’s 1948 declaration of independence defined the country as a Jewish and democratic state, and the government says the recently passed bill merely enshrines the country’s existing character.But critics say it undercuts Israel’s democratic values and sidelines the country’s non-Jewish population, namely the Arab community that makes up 20 percent of the country.

One clause downgrades the Arabic language from official to ‘‘special’’ standing.

Ayman Odeh, an Arab member of the Israeli Parliament, said: ‘‘This is the first time that tens of thousands of Arabs have come to Tel Aviv with Jewish democratic groups. They came to say this is not the end of the demonstrations, but the first serious demonstration against the Nation State law.’’

Many Jewish Israelis, including top retired security officials and politicians, have also harshly criticized the law.

Israel’s Arab citizens enjoy full citizenship rights but face discrimination in some areas of society like jobs and housing. They share the ethnicity and culture of the Palestinians in the West Bank and Gaza Strip and often identify with Palestinian nationalism, rather than Israeli.

Associated Press