Technically, they were. As were the Minutemen at Concord and beyond.
Personally, I’m glad they were.
Terrorism is a tactic of instilling fear, especially of a population. The Concord militia were defending the potential stealing of powder and weapons by the Brits. They don't seem equal in any way.
The Americans in 1776 were a legitimate army fighting by codes of war. The Jewish groups in Palestine 1944-48 were not.
You can be a rebel without being a terrorist. The Minutemen defended their weapons and powder from British troops. They shot at soldiers. That's not a terrorist act. The PLO hijacked and blew up a bus full of children. Their goal was to kill innocent noncombatants. That is a terrorist act. I would definitely not generalize and apply the word "terrorist" to all Jewish activists in Palestine at that time, nor am I convinced that even a majority of those working for a Jewish state were terrorists.