I stumbled across this rally as I wandered around Istanbul. There was a large police presence outside this park to keep order. It was interesting to watch for a little bit, but my inability to speak Turkish hampered my ability to understand the particulars of this. I think the presence of Palestinian flags betrayed the general sentiment of the crowd.
Dolmabahçe Palace was the home of the last sultans of the Ottoman Empire and was used as Atatürk's residence during his presidency.