The area, known to Muslims as the Haram al-Sharif, or the Noble Sanctuary, and to Jews as the Temple Mount, has been a frequent flashpoint for conflicts before, with even low-level scuffles escalating into drawn-out battles.
Sherine Tadros, reporting for Al Jazeera from Jerusalem on Sunday, said: "This was all sparked early this morning when - according to the Israeli police - there was a group of tourists entering the al-Aqsa compound in the Old City.
"They were pelted with rocks by the Palestinian demonstrators [who] decided to keep on with their resistance to the entry of these tourists into the Haram compound.
"That sparked clashes outside and near the area, which has resulted in an escalation ... outside the walls of the Old City."
Reporting later from the scene, our correspondent said: "There's a heavy police presence but it does seem calm now."
A visit to the al-Asa mosque compound in 2000 by Ariel Sharon, then an Israeli opposition leader and later prime minister, is blamed for igniting deadly clashes that escalated into the popular Palestinian uprising known as al-Aqsa Intifada.