Campaigners staged a blockade at an aerospace firm in Dorset.
The Workers for a Free Palestine group protested at the entrances to Eaton Mission Systems in Wimborne.
The factory makes air-to-air refuelling systems which the group says are used by the Israeli military.
The BBC has contacted the company for comment. Other demonstrations are also being held at defence factories in Brighton, Lancashire and at BAE Govan, Glasgow.
The group said it had more than 600 people at the protest including health workers, teachers, hospitality workers, academics and artists.
The demonstrators are urging the firm and other companies to end their ties with Israel and cease all weapons, defence and supplies trading with them.
Protesters were seen holding a banner saying: “Weapons made here kill in Gaza.”
Mesh, a junior doctor who did not want to give his surname, said: “I felt compelled as a health worker to stand in solidarity with healthcare workers in Gaza… by trying to stop the UK arming of Israel.”
Emergency department doctor, Harriet, who also did not want to give her surname, said: “It’s heartbreaking, we feel helpless as a profession.
“We come to work every day and you can see people becoming more and more broken by it.”
Dorset Police said it was aware of the protest and officers were “at the scene liaising with the organisers to ensure people can exercise their right to protest legally and safely without causing significant or ongoing disruption”.
“We respect people’s right to lawful protest and will seek to facilitate a peaceful protest, but public order or criminal offences will not be tolerated and will be dealt with robustly,” the force added.
Source : BBC