He said: "You can't call buskers beggars and then licence a select few of them.
The London Public Entertainers Collective is campaigning for the right for buskers to perform wherever they want on the London Underground network.
Buskers are currently not allowed to play anywhere in the Underground.
One of the protestors, Bongo Mike, said: "We want busking to be decriminalised, then we want consultation and compensation."
However, from the autumn, some buskers will be allowed to play in the network if they have official approval.
The six-month trial scheme will be launched at eight stations across the capital.
The change in policy will enable the London Underground to pick and choose who busks in its stations - a requirement being that the busker must be able to play well.
'Total hypocrisy'
The protesters say they are angry that only classical musicians will be licensed.
Buskers who have not been approved by the London Underground will continue to face fines and prison sentences.
Bongo Mike, who plays the guitar, bongo and whistles, has campaigned for several years for a change in the law.
He said: "You can't call buskers beggars and then licence a select few of them.
"The whole thing is a total hypocrisy."
In May, Julian Lloyd Webber, the acclaimed cellist and brother of composer Andrew, became the first official busker on the London Underground.
He entertained commuters by playing a selection of tunes from his brother's musicals at Westminster Tube station.
'New outlet'
Mr Lloyd Webber predicted the Tube could become a new performing outlet.
He said:¿ I think it is good that there should be some quality control.
"The last thing that you want if you have got a headache or a hangover is someone who cannot play.
"There are a lot of really good music students coming out of colleges and the Tube is definitely a new performing outlet that they could use," he added.
A London Underground spokesman said the change in policy was prompted by the discovery that London's commuters wanted to listen to good-quality busking while using the Tube.
The buskers will spend the day outside Covent Garden station singing their protest song "Don't Know Why".