His move came as members of a community Facebook group suggested a rush-hour blockade of Leith Walk in protest at the planned extension.
Cllr Ritchie warned that 18 months of disruption during construction of the line from York Place down Leith Walk and along to Newhaven would make it impossible for many businesses to trade normally.
Cllr Ritchie, who quit the SNP earlier this year amid allegations of sexual harassment, said: “If you go up Leith Walk just now it’s like Las Ramblas in Barcelona – amazing cafés, bars, artisan shops. It’s the jewel in the crown of what Edinburgh has to offer commercially. They are not going to survive. The cost of the trams will be people’s livelihoods and businesses. Someone has to speak up for these people and these businesses.”
The council has already approved the extension in principle, but the final decision on whether to go ahead with the £165 million project is expected in the autumn.
Only the Conservative group on the council is currently opposed to the extension.
Cllr Ritchie, who represents Leith Walk, said he had written the SNP manifesto for last year’s council elections, which supported the extension in principle, but laid down conditions which must be met before it goes ahead.
He said: “There was a mood in the group in favour of the extension. I urged very strongly there should be three protections – the business case should be suitably robust, businesses would be protected and disruption would be kept to a minimum.
“If you look at the business case I think it’s quite flimsy; and so far no details have been given about the business compensation, but from talking to people I don’t think it’s going to be anywhere near what I thought and what businesses have a right to expect.”
He has started a Facebook group Leithers Against The Tram, which describes itself as a “grassroots community campaign standing up for local businesses and residents who oppose spending millions of taxpayer money on extending the tram”.
Meanwhile, an online post has encouraged users to form a vehicle barrier from 8am on Monday, May 7 to cut off transport services to the area.
The user called for residents to block off Leith Walk “from Pilrig down”. And the angry post signed off: “Leith don’t want the trams!”
Another user supported the move, posting: “Edinburgh already have better public transport than most other cities and that money could’ve been spent on fixing the roads.
“The trams have only created a longer commute through the city and this will make commuting though to work even worse. Feels like we’re going backwards.”
However, most members of the page were not convinced the planned protest was a good idea.
One wrote: “Trams are key to unlocking the full potential of Ocean’s Terminal and the other brownfield sites in north Edinburgh along Newhaven and Granton.
“They will encourage positive investment and get rid of cars as well.”
Another agreed, adding: “I want the trams, wish they would hurry up and get on with them.”
A third member posted: “I think that’s conclusive. Leith want the trams, need the trams and will benefit greatly from the trams. It’s like everything in life, no pain no gain.”
In March, a council survey found 59 per cent in favour of extending the line, and 42 per cent said the new line would “benefit local businesses”.