Laws brought in this March allow police to bring in the sellers for questioning, and up to 550 have been taken in since then.
Mercier said the reinforced police presence has been in place for several months, but it was only yesterday that the sellers had dispersed.
Clashes began on Friday after one of the street sellers was electrocuted on a metro line while running from the police. His life is no longer in danger, but vendors were outraged.
As the police moved forward on Friday evening, the sellers retreated into the darkness, some of them shouting "racists". Three policemen were injured on Sunday by projectiles thrown by street sellers.
Most of the illegal sellers come from sub-Saharan Africa or the Indian sub-continent.
They have a knack of catering to their customers' needs. At dusk, they bring out alcohol; when it rains, they produce umbrellas, most of them still carrying several rings of Eiffel Tower souvenirs of all different sizes as well.
Mercier said the illegal sellers have told him they can make up to €500 (NZ$866) day.
Police figures show there are sometimes up to 300 vendors under the Eiffel Tower.
"They are more numerous than the tourists," said Ivan Bratacos, who runs a souvenir stall on Place de Trocadero.
"Their numbers have tripled in the last three years and our profits have gone down 300 per cent in that time."
In the Eiffel Tower's official shop, a mini tower costs €2; the street sellers charge €1 for five. The relations between the street sellers and local stall-holders have got worse as the number of street sellers has increased.
Shopkeeper Ali Gamon has a scar on his head about a centimetre long. He said he had to have eight stitches after a street seller hit him with a 40cm Eiffel Tower a couple of years ago.
"We're dying," said another souvenir shopkeeper.
"This is the last year for us. We can't stand up against them financially."
But the street sellers - many of whom police say are in France illegally - retort that they have to work to make a living and provide for their families.
"It's not legal what we do, but we don't have a choice," said one, a refugee from Guinea, who wished to remain anonymous.
"We don't have the papers to work, but we need to make a living."
- INDEPENDENT