Protesters are expected to mount a wave of demonstrations during Barack Obama's state visit.
Stop the War Coalition (STWC), the Campaign for Nuclear Disarmament and Justice for Bahrain have all announced plans to protest during President Obama's three-day visit.
Anti-war organisers said they expect hundreds to attend a demonstration outside Buckingham Palace tomorrow evening, when Mr Obama will be enjoying an official banquet with the Queen.
An SWTC spokesman said the protest would decry the Afghanistan and Iraq wars as well as the United States' intervention in Libya.
"Obama doesn't inspire the same degree of anger as George Bush did, but it is important to have a protest against what is in many ways a continuation of Bush policy in America," the spokesman said.
"We are still seeing bombing in Afghanistan and know that under Obama, the number of drone attacks in Pakistan has actually increased."
The groups said they expected there to be speeches against the wars, as well as calls for Mr Obama to engage with the peace process in the Middle East.
A Justice for Bahrain spokesman, who wants to use the protest to draw attention to the unrest occurring in his country, said: "We will be shouting, 'Obama, shame on you, shame on you, shame on you'."
A "Black Bloc" anarchist action, coinciding with the Obama visit, has been delayed for a week.
Tensions between police and protesters are at a high after 55 demonstrators were arrested on the day of the Royal Wedding, most under Section 60 "stop and search" powers. A CND spokesman said there was now a perception of a "higher risk" in protesting, but activists would not let police tactics put them off.
A Scotland Yard spokesman said: "We will be policing Buckingham Palace, but we can not discuss any security measures for the US president coming into the country, for obvious reasons."Reuse content