The incident involved 32 fishing vessels, police said in a statement. Twelve boats displayed banners near the Houses of Parliament for 20 minutes as part of their protest before traveling back out to sea, the Metropolitan Police said in a statement to ABC News.
“There were around 15 small ribs of counterdemonstrators who traveled alongside them," police added, saying "the demonstration was good natured on both sides."
The initial demonstration was organized by fishermen and activists who are part of the Fishing for Leave campaign, which believes that EU fishing quotas are unfair.
They were joined by U.K. Independence Party leader Nigel Farage, who is campaigning for Britain to leave the EU.
"Today's flotilla is not a celebration or a party but a full-throttled protest. We want our waters back," he said in a statement.
"There are now many harbors without a single commercial vessel. Not satisfied with that, the EU is now regulating our recreational sea anglers," Farage said. "This is now leading to a loss of jobs in our charter angling fleet."
Geldof released a statement to the Press Association in which he wrote, "Farage is no fisherman's friend."
"The U.K. gets the second-biggest quota out of member states and has the biggest profit of any EU member state," Geldof said, adding that leaving the European Union would be "disastrous for our country, our economy, our public services and our fishing industry."