Israel's ruling coalition, led by Prime Minister Benjamin Netanyahu, had announced July 1 as the date to begin moving forward with the plan to impose Tel Aviv's "sovereignty" over about a third of the West Bank, including settlements and the fertile Jordan Valley.
Similar demonstrations also took place in the West Bank cities of Ramallah and Jericho.
Factions in Gaza agreed last Sunday on a national work plan to confront US President Donald Trump's Deal of the Century.
Thousands of Palestinians protested Wednesday in Gaza against Israel's West Bank annexation plans, as premier Benjamin Netanyahu held off an announcement on the controversial project and worldwide opposition stiffened.
America's allies oppose annexation.
Her comments come as Israel's Prime Minister Benjamin Netanyahu said talks were continuing with U.S. officials on the "application of sovereignty". He noted his long links to Israel, dating back to when volunteered on a kibbutz as an 18-year-old and his many visits since then.
Writing in Israel's Yedioth Ahronoth newspaper on Wednesday, Britain's Prime Minister Boris Johnson said that although he was a "passionate defender of Israel", he viewed annexation as "contrary to Israel's own long-term interests". The American Administration is using significant pressure as leverage in order to bring Netanyahu to agree to the initial outline of the Trump plan without including the necessary changes. "If it does, the United Kingdom will not recognise any changes to the 1967 lines, except those agreed between both parties", he wrote. The worldwide community considers the territory occupied land, and Israel's more than 120 settlements there illegal. For decades, Jewish settlements in the West Bank have expanded, jeopardizing any possible establishment of a sovereign Palestinian state alongside Israel.
Also on Wednesday, Palestinians held "Day of Rage" rallies both in the West Bank and the Gaza Strip against the Israeli expansionism.
Palestine Solidarity Network Aotearoa chairman John Minto said the group had written to MPs asking them to endorse Foreign Affairs Minister Winston Peters' "serious concern" about the proposed annexation, send messages of support and attend a protest if they could. The global community considers the area occupied and its settlements to be illegal.
Ynet journalist Elior Levy said that Hamas unconventionally launched a volley of rockets towards the sea, a matter thought to be a warning for Israel against annexation.