Israeli troops have used teargas and rubber bullets against a group of protesters at a section of the controversial barrier in the West Bank.
Israel's barrier has prompted Palestinian protests
Several people were injured and about 10 arrested in the incident near the village of Budrus, outside Ramallah.
Palestinians, an Israeli and several foreign nationals were said to be among those detained.
Israel says the barrier is designed to prevent suicide attacks, while the Palestinians say it is a land grab.
Hundreds of demonstrators, including members of the pro-Palestinian International Solidarity Movement and the International Women's Peace Service, were at Budrus on Wednesday.
Some reports say the protesters threw stones at the Israeli soldiers, who returned fire using rubber bullets and tear gas.
Protester Ted Querbath, from New York, said he saw six people wounded when the army started shooting rubber bullets and tear gas.
"A Palestinian woman was severely beaten up and bleeding on her head," he told Reuters news agency.
Palestinian medics said 20 Palestinians were hit by rubber bullets and taken to hospital while an Israeli woman suffered a slight leg wound.
Swedish MP Gustav Fridolin was among the foreign nationals arrested, according to the French news agency AFP.
South African protester Anna Weekes said Mr Fridolin was arrested by soldiers as he sang pro-Palestine songs with a group of local schoolchildren.
"We were sitting on a terrace singing Free, Free Palestine. Then they grabbed various internationals," she said.