The call appeared to pre-empt an attempt by Qatar to hold an Arab summit in Doha on Friday that Saudi Arabia and Egypt have refused to attend, preferring to hold consultations on Gaza on the sidelines of Arab economic summit in Kuwait next week.
Saudi news channel al-Ikhbariya, which reported the summit call in Riyadh, gave no more immediate information.
Hesham Youssef, an aide to the Arab League chief Amr Moussa, told Saudi-owned Al Arabiya television only 14 countries had agreed to the summit, contradicting a Qatari claim earlier that 15 states had agreed, making up the required 15-state quorum.
With the death toll in Gaza edging towards 1,000, the tug-of-war over summit plans have underscored deep divisions in the Arab world over Palestinian armed resistance to Israel and challenging the United States, which back most Arab governments.
Conservative Arab governments are wary of summits at times of crisis because they are reluctant to pass confrontational resolutions which would meet the expectations of people who have protested across the region for the past two weeks.
Egypt, the only Arab state bordering Gaza, has also faced Arab criticism for cooperating in the Israeli blockade of Gaza.
Egypt has blamed Hamas for provoking Israel with rocket attacks. Saudi Arabia has refrained from openly blaming Hamas but writers in semi-official papers have accused Hamas of allying with Riyadh's bete noire, Shi'ite power Iran.