Pro-Palestine protesters forced police to close Tower Bridge on Saturday evening.
Flares were set off and traffic blocked in demand of a ceasefire in Gaza.
Activists were seen waving Palestinian flags and carrying a banner that read “Save Gaza, Ceasefire Now” as they marched across the bridge.
Drummers appeared to lead the march, pounding out a beat as protesters clapped and chanted “free, free, Palestine”.
The bridge was cleared after City of London Police responded to the rally and seemingly moved in to disperse the protesters.
A spokesman said: “Tower Bridge reopened at around 6.25pm following an earlier protest.
“Thanks to Metropolitan Police for their assistance.”
There have been arrests but Scotland Yard said the “overwhelming majority” were peaceful and acted lawfully.
Meanwhile, significant progress has been made in hostage talks in Paris, according to Israeli media.
United States, Israeli, Qatari and Egyptian officials have arrived in the French capital for negotiations including a possible ceasefire.
They are hoping to head off an Israeli assault on the Gaza city of Rafah where more than one million displaced people are sheltering.
Hamas leader Ismail Haniyeh met Egyptian mediators in Cairo to discuss a truce this week on his first visit since December. But talks reached an impasse.
Gaza’s death toll reached 29,606 on Saturday as 92 more people were killed in a single day.
Figures from Gaza’s health ministry, say nearly 70,000 people have been wounded by the war.
Northern Gaza is almost entirely cut off from the outside world and more than 7,000 people remaining missing.
Speaking on Friday, Hamas political official Osama Hamdan said the militant group has “dealt positively with the proposals and initiatives of the mediators” but that Israel’s position “poses many obstacles to reaching an agreement”.
But Israeli prime minister Benjamin Netanyahu has called the militant group’s demands “delusional”.
