Israel did not publicly confirm the deal.
The procession started in Portland Place and protesters marched through Oxford Circus and Trafalgar Square to reach Downing Street where the government offices are located.
They heard speeches from union officials, MPs and campaigners.
"Palestine has the right to exist but sadly that is a right that is increasingly threatened", said Labour MP Richard Burgeon. "From the river, to the sea, Palestine will be free", she said. He said the case of Palestine was not an issue of "Right' versus "Left" but a matter of "Right" and "Wrong".
Palestinian ambassador to the UK Dr Husam Zomlot stood on the stage next to Ahed Tamimi, the protester who became a globally known after slapping an Israeli soldier in the West Bank a year ago. "We will not be made victims!" Efforts continue in the U.S. and Europe to suppress free speech by falsely labelling criticism of Israel as 'anti-Semitic'.
Labour Party leader Jeremy Corbyn sent a message of support on Twitter."We can not stand by or stay silent at the continuing denial of rights and justice to the Palestinian people", Corbyn wrote.
"Expressing its full solidarity with the Palestinian people's cause, the Islamic Republic of Iran once again underlines the important responsibility of the worldwide community, in particular the United Nations, to end the organized occupation of Palestine and the Holy Quds (Jerusalem) and to help the people of this land determine their own destiny and form an independent state", the statement added.
The Trump-Netanyahu axis of evil is an ongoing disaster for theindigenous people of Palestine, the Palestinians.
More than 750,000 Palestinians fled or were expelled in fighting during the creation of the Israeli state, and millions of their descendants now scattered around the world demand the right to return to their historic homes. As our audience increases - so do our costs. "We want them to lift the siege so we can work".