The man, who is barefoot and holds a Palestine flag, has been spoken to by negotiators several times but at 10.30pm had not yet agreed to come down.
The United Kingdom-based activist group Palestine Action said it "rejects Donald Trump's treatment of Gaza as though it were his property to dispose of as he likes."
A 29-year-old man has been charged after climbing onto the clock tower of Big Ben, Metropolitan Police said. Daniel Day, of Palmerston Road, Westcliff-on-Sea, Essex, has been charged with intentionally or recklessly causing a public nuisance and trespassing on a protected site.
A barefoot man who scaled Big Ben's tower with a Palestine flag has been on the building for more than seven hours.
Activists targeted a Trump-owned golf course in Scotland early on Saturday morning, painting "Gaza Is Not For Sale" on the lawn
Some results have been hidden because they may be inaccessible to you
Show inaccessible results