TEHRAN, Iran - Students at Amir Kabir University in Tehran defied threats of a crackdown and protested for a fifth day yesterday against the death sentence ordered for reformist history professor Hashem Aghajari.

Aghajari thumbed his nose at Iran's judiciary yesterday by refusing to appeal his sentence, which has become a rallying point for Iranian reformists who oppose strict rule by Islamic clerics.

"If the head of the judiciary thinks that this verdict is fair, he should apply it. Otherwise, they should do the necessary" and overturn it, Aghajari's attorney, Saleh Nikbakht, quoted the professor as saying, to applause from students at the noontime rally.

Aghajari was sentenced to death last week for insulting Islam and its leaders in a speech this summer in the western Iranian city of Hamedan. In his address, he called for an end to blind obedience to Iran's religious rulers.

Iranian President Mohammad Khatami, a reform leader with whom Aghajari is allied, called the sentence "improper" yesterday, according to Iran's state-run news agency. "Given that this ruling should never have been issued at all," he said, "I hope this matter will be settled in a favorable manner."

More than one student speaker at yesterday's rally called for secular democracy.

Many students at the demonstration hadn't been born when alumni from their school seized the U.S. Embassy in the Iranian capital 23 years ago and held its occupants hostage for 444 days. Those students helped usher in the Islamic revolution.

Like their predecessors, the 1,200 students who attended the peaceful rally yesterday at the small, conservative Islamic university appeared determined to redefine their nation in the eyes of their countrymen and the world.

"Religious democracy is in contradiction to the real democracy that we are talking about," said Mehdi Habibi, president of the Islamic Student Union.

Iranians have been pushing for more social and political freedoms in the past decade and have twice elected Khatami for his pledges to bring about such reforms. But hard-line religious leaders, who have the final say on laws and control the judiciary, the military and the news media, have refused to significantly relax their control.

The mood at yesterday's rally was tempered by fears of arrest and of hard-line militants, who often crack down on protesters. Organizers repeatedly appealed for calm and restraint in directly criticizing Iran's supreme leader, Ayatollah Ali Khamenei. "Don't give them the pretext to attack us," one student speaker said.

Khamenei warned Tuesday that he may resort to "popular force" - a reference to the militia - to end the growing protests. Militia forces quelled the last wave of student uprisings in 1999, in which one student was killed and many more were arrested.

This week's demonstrations have been peaceful. Young men sat with young women, who wore traditional black cloaks or dark scarves on their heads in accordance with Islamic law.

A single poster was propped up near the speaker's stand, featuring Aghajari's photograph with the caption: "The punishment for thinking is execution." A hangman's noose was affixed to the poster.