The Friday protest in Galatasaray Square included members of the Chamber of Architects and Engineers, who also helped lead the Taksim Solidarity Platform that initiated the protests over the demolition of Gezi Park in Istanbul.
The bill gives the Urban Planning Ministry full authority over all urban projects.
A representative for the protesters told Hurriyet Daily News the legislation was a sign the government wanted to "silence" architects and engineers to prevent hurdles in grandiose urban projects.
"They don't want us because we are against [Istanbul's] third bridge, because we said no to Canal Istanbul," the spokesman said, referring to large-scale construction works branded as "crazy projects."
During his speech, the crowd chanted "no to the third bridge, no to canal Istanbul, no to crazy projects," hinting the demands of the protesters could widen.
The newspaper said journalists marched at Galatasaray Square, voicing concerns about threats they perceive to journalistic freedoms. Walking behind a banner featuring penguins, they shouted, "Free press cannot be silenced."
Other banners read, "Let us do our job," "End the pressure," and "Don't target, don't detain, don't arrest, don't threaten, don't censor."
The journalists say there have been the arbitrary detentions and arrests, firings and censorship since the demonstrations began.