'Gates of hell'
Eissa, who had been convicted by a lower court in March and sentenced to six months in prison, told the AFP news agency that the court ruling "opens the gates of hell for the Egyptian press and confirms the state's hostile position towards freedom of opinion and expression".
He said: "This verdict isn't just about freedom of the press and freedom in this country. This proves that anything concerning the president is a sacred and untouchable matter.
"In this country, it's normal for journalists to be jailed while businessmen are freed," he said in reference to an acquittal in August of five defendants over a 2006 ferry sinking in which more than 1,000 people died.
Amnesty International, the London-based human rights group, had earlier denounced the trial, saying it was part of a "pattern" by Egyptian authorities who bring criminal charges against journalists to "chill" media freedom in cases of public interest.
The Egyptian Hisham Mubarak Legal Centre, a human rights organisation, said that sentencing Eissa to jail for a publishing offence went against international treaties signed by Egypt to protect press freedoms.
The Arabic Network for Human Rights Information had earlier released a statement saying it hoped Mubarak would use his authority "to end the trial as he did several times by pardon or retrial".
"This case reminds us of the president's promise made four years ago to end imprisonment on crimes related to press publishing," the statement said.
Speculation about Mubarak's health was widely reported in Egypt's independent press and included reports he had been sent to hospital, travelled abroad for treatment and some suggested he had died.
At least seven journalists were sentenced to up to two years in prison in September 2007 on charges ranging from misquoting the justice minister to spreading rumours about Mubarak.
More than 20 newspapers suspended publication for a day in protest over the crackdown.