Female drivers in Saudi Arabia will be dealt with "strictly", authorities said on Thursday before a right-to-drive campaign culminates at the weekend.
The kingdom is the world's only country where women are not allowed to operate cars.
Activists said in early October they were revving up their campaign using social media.
But the interior ministry said it will "strictly implement" measures against anyone who "contributes in any manner or by any acts, towards providing violators with the opportunity to undermine the social cohesion".
The statement was carried by the official Saudi Press Agency.
Activists have encouraged women to post pictures of themselves driving on Twitter under the hashtag #IWillDriveMyself, as well as on Instagram, YouTube and WhatsApp.
More than 2,700 people have signed an online petition at www.oct26driving.com.
Activists told AFP that every day "two or three" women have shared pictures of themselves driving via WhatsApp.
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But they say nothing special is expected for the campaign's peak on Sunday.
"We just ask the ladies who need to drive, to drive as usual on the 26th" or on another day, said one activist, Nasima al-Sada.
Aziza al-Yussef, who says she runs errands in her car two or three times a week, said the campaign was about "raising the voice" and making their demand heard -- but not by doing anything illegal such as a demonstration.
Activists argue that women's driving is not against the law.
Tradition and custom are behind the prohibition, which is not backed up by an Islamic text or judicial ruling, the online petition states.
Last year, activists also focused their demands on October 26 -- which they simply call a "symbolic" date as part of efforts to press for women's right to drive.
At least 16 were fined for taking the wheel on that day.
Saudi women still need permission from a male guardian to work and marry, while restaurants are divided into "family sections" and separate areas for single men.
The ultra-conservative Wahhabi Islamic tradition is predominant in the kingdom, where it applies to both religious and political life.