The United States is leading calls for Sisi to pardon the journalists working for the Qatar-based network who were convicted yeseterday of aiding the blacklisted Muslim Brotherhood Islamist movement and "spreading false news".
Eleven defendants tried in absentia, including one Dutch journalist and two British journalists, were given 10-year sentences.
A presidency official told AFP that Sisi cannot legally pardon the journalists until a final court ruling after an appeal.
Sisi said today he had called the justice minister to stress that the authorities "will not interfere in judicial matters".
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The verdicts sparked an international outcry, with Australia saying it was "appalled" and US Secretary of State John Kerry denouncing "a chilling and draconian sentence".
Today, Sisi said in a televised speech at a military graduation ceremony: "We have to respect judicial rulings and not comment on them even if others don't understand them."
Al-Jazeera says only nine of the 20 defendants are on its staff.
Sixteen defendants in the trial are Egyptians who were accused of belonging to the Brotherhood, which the authorities designated a "terrorist organisation" in December.