RIYADH, Saudi Arabia — Hackers defaced their website. Delegations of clerics appealed to the king to block their movement. And men claiming to be security agents called their cellphones to leave a clear message:

O, women of the kingdom, do not get behind the wheel!

But they did anyway. On Saturday, a small number of women — even the main activists were not sure how many — insisted on violating one of the most stubborn social codes in staunchly conservative Saudi society, getting into their cars and driving. Many posted videos of themselves doing so to spread the word.

“We are looking for a normal way of life,” Madiha al-Ajroush, 60, a psychologist, said in an interview in Riyadh, the Saudi capital, “for me to get into my car and do something as small as get myself a cappuccino or something as grand as taking my child to the emergency room.” The public call for women nationwide to drive on Saturday was the latest push in a decades-old effort by a small group of activists to exercise what they see as a fundamental human right. Saudi Arabia, a hereditary monarchy, is the only country in the world where women are not allowed to drive.

The fact that the activists have been at it for so long without succeeding in creating a mass movement or any change in government policy underlines the power of tradition in Saudi society and the tremendous political clout of social conservatives who fear that Westernization or anything that looks like it will detract from the kingdom’s Islamic character, even though malls, high-end shops and fast-food outlets are noticeable across the Saudi landscape.

Despite the strong opposition, the women believe time is on their side. They point to the huge numbers of Saudis who study and travel abroad and return with new perspectives on their culture. They also suggest that the kingdom’s youthful population and the tremendous rise of social media will, over time, make the country more open to change.

But their movement’s goal is profoundly modest compared with the Arab Spring calls for reform that have toppled some Middle Eastern governments and shaken others. They have gone out of their way to avoid anything that looks like a protest, remain deeply loyal to the 89-year-old King Abdullah, and studiously avoid confrontations with the authorities.

“We don’t want to break any laws,” said al-Ajroush, who has been campaigning for the right to drive since 1990. “This is not a revolution, and it will not be turned into a revolution.”

The call for women to drive on Saturday led to an explosion of comments and arguments in Saudi social media.

The Interior Ministry last week warned against all acts that “disturb the social peace and open the door to discord.” A new statement Friday threatened punishment for anyone involved in “assemblies and banned demonstrations calling for women to drive cars.”