Crowds started congregating at about 1pm on Sunday ahead of an expected march organised by campaign group Keep Britain Free.
They initially hovered around Marble Arch in the capital to listen to speeches for around two hours.
People held placards reading "I will be not be masked, tested, tracked" and "no mask".
During the coronavirus pandemic, masks have been made compulsory on public transport in the UK.
Face coverings will also become mandatory in shops and supermarkets in England from July 24.
Those who fail to wear a mask face fine of up to Â£100.
Keep Britain Free claims it sees the new regulations as an impingement of civil liberties.
One of the organisers, Leah Butler-Smith, who was attending the protest said the group is not concerned about people who choose to wear a mask.
"It is just the fact that people are being told they have no choice about wearing a mask," she told Sky News.
"Because the Government started out saying 'there is absolutely no need for a mask', and many other important scientists have reportedly said the same, it did not make any sense why they suddenly said it was going to be mandated," she added.
"If the Government really wants to protect the public and give them more confidence then they should stop trying to use the coercion strategy or to make people scared."
Asked whether she believes other governments around the world which are advising wearing face masks to prevent transmission, Ms Butler-Smith said: "I would believe them if they did not keep changing their mind every five minutes."
She also said that she had no intention of wearing a mask and would not accept a fine, because it would not be "valid".