Israeli Police Inspector General Yochanan Danino and Public Security Minister Yitzhak Aharonovitch agreed to add about 40 officers to try to ensure calm, The Jerusalem Post reported Friday.
The Post said a high alert was expected to last through Shavuot, which begins at sundown Saturday.
An 18-year-old Tel Aviv resident was arrested Friday on suspicion he belonged to a gang that targeted African migrants. The Post said the gang allegedly had assaulted migrants and police Wednesday night and looted stores belonging to Africans.
Twelve youths from south Tel Aviv were taken into custody on suspicion of assaulting African migrants in the area. Police said they suspected some victims were beaten with clubs and others assaulted with pepper spray.
Residents demonstrated Wednesday against the influx of immigrants.
Political leaders condemned the violence while pledging a crackdown on illegal immigration, The New York Times said.