UN Secretary General Antonio Guterres has called on Israel to immediately halt its operation, saying it was “fuelling an already explosive situation”.
He urged Israeli forces to “exercise maximum restraint and use lethal force only when it is strictly unavoidable”.
The IDF said the five Palestinians were killed after “exchanges of fire” in Tulkarm.
It identified one of the fatalities as Mohammed Jaber – also known as Abu Shujaa – who was reportedly the local leader of the Palestinian Islamic Jihad militant group.
The IDF said Jaber was linked to a number of attacks on Israelis, and was planning more.
The deaths came on the second day of what Israeli media say could be a days-long operation.
The Israeli military said it also made arrests and seized weapons.
Homes and infrastructure were damaged in the attacks, Palestinians said.
It is the largest such action in the West Bank since the days of the second Palestinian intifada, or uprising, two decades ago.
