The shadow chancellor had appeared to back the plan to flood central London with up to one million people to mark the Queen's Speech, when he spoke to the Bakers' Union conference last week, and called for Britons to "get out on the street" to mobilise against the Tories.
Today, however, McDonnell said the label "day of rage" was "not the right expression" and called on activists not to break the law.
"You can be angry, but they mustn't resort to violence," McDonnell told the Today programme.
"If you want to see what effective protest is all about, follow the lead of Gandhi, not others".
A left-wing group called the Movement For Justice By Any Means Necessary is due to meet at 11.30am in Shepherd's Bush before marching on parliament.