The information on Friday about the number of people arrested at the protest comes from a lawyers' group called CHD, which monitors and defends human rights in Turkey.
Authorities in Istanbul declined to comment on the information.
The demonstration in Istanbul, organized by trade unions, was surrounded by riot police.
Two marches headed for the symbolic Taksim Square, prompting police to completely block the square.
The anti-regime demonstrations in Istanbul were accompanied by similar protests across Turkey.
