The people gathered in East al-Quds (Jerusalem) on Saturday.
Shalabi has refused to eat for 31 days in protest to her detention without any charge or trial.
The protesters have staged a sit-in in front of the office of the International Committee of the Red Cross to voice support for Palestinian activist.
On Wednesday, Richard Falk, the UN Special Rapporteur on Palestinian human rights, called on Tel Aviv to release Shalabi.
Shalabi was among those Palestinians released in a prisoner swap deal between Tel Aviv and Hamas last year, but she and several others were rearrested a few week ago.
Palestinian Prisoners’ Club, a non-governmental organization, reported on Tuesday that dozens of Palestinian prisoners held in Israeli jails have joined a hunger strike to show support for Shalabi.
According to the Palestinian Central Bureau of Statistics and prisoner advocacy groups, there are currently thousands of Palestinian prisoners in Israeli jails, many of whom have been rounded up without charge or trial