Yellow Vest demonstrators were filmed reacting with anger after James Goddard’s arrest in London.
Supporters of the pro-Brexit activist were filmed chanting, and footage appears to show them burning an EU flag.
A red flare was also set off as protesters gathered, and backers chanted “Shame on you” at officers.
Goddard, originally from Leicester, was taken to Holborn Police Station yesterday morning.
It is understood his arrest was in connection with Remainer MP Anna Soubry being harassed outside Parliament.
A Metropolitan Police spokesman later told Mirror Online that a man in his 30s had been released on bail until early next month.
His supporters claim he was preparing to hand himself in at Holborn police station at midday the same day.
The Met Police said in a statement earlier today: “We can confirm that a man in his 30s was arrested at 11.42am on Saturday, 12 January outside St James’s Park Tube station on suspicion of a public order offence.”
Pro-Brexit and far-right campaigners have held a number of protests recently in London, including demonstrations outside Parliament.
Some 115 MPs wrote to Metropolitan Police Commissioner Cressida Dick this week after demonstrators hurled abuse at female MPs.
Earlier this week pro-Remain MP Anna Soubry was subjected to abuse outside Parliament, but police have not confirmed whether this is connected to the arrest.
Goddard recently asked his supporters for donations to his PayPal account, claiming the money would let him “go the extra mile” after vowing to target Remain-backing MPs six days a week until Britain leaves the EU.
The PayPal account was later deleted.
So were Facebook pages and groups under Goddard’s name, said Facebook.
A Facebook spokesman said earlier: “We have removed James Goddard’s Facebook pages and groups for violating our policies on hate speech.
“We will not tolerate hate speech on Facebook which creates an environment of intimidation and which may provoke real-world violence.”