Cartier owner Richemont said "yellow vest" protests in France weighed on its sales momentum in the last three months of 2018.
This was despite the fact that growth in key markets like China kept up at a healthy pace.
Richemont's softer sales come amid worries that Chinese appetite for big-ticket items could wane as its economy slows, with investors on edge after a recent Apple warning over weaker iPhone sales in the country.
Growth in Swiss watch exports, the best available indicator for demand in the sector, has slowed in recent months.
Switzerland's Richemont, the world's second biggest luxury goods group, posted a 5% rise in sales at constant currencies in the October-December period, its third quarter.
The figures excluded recently acquired online distributors Yoox Net-A-Porter (YNAP) and Watchfinder, a second-hand platform.
That marked a slight slowdown from the 8% growth in the six months to the end of September, though it was in line with consensus estimates cited by analysts.
"Sales grew in all regions, with the exception of the Middle East and Europe," Richemont, which also makes Van Cleef & Arpels jewellery, and owns IWC watches and fashion brand Chloe, said today.
It added that the anti-government protests in France, which erupted as a backlash over high-living costs and hit central Paris in the run-up to Christmas, "negatively impacted tourism and led to store closures for six consecutive Saturdays".
French companies have this week revealed some €60m of lost business from the anti-government demonstrations that have been marred by violence.
Richemont is the first major firm in the sector to provide a glimpse of trading trends in the last three months of 2018.
Louis Vuitton owner LVMH reports results on January 29.
Richemont said sales were still progressing at a healthy pace in mainland China, citing "double digit" growth, but it did not give further details. Revenues grew 10% in Asia Pacific as a whole.
But it added that sales growth had slowed in Hong Kong, the biggest market in the world for watches.
Falls in the yuan last year squeezed Chinese consumers' purchasing power in overseas markets, even as more are splurging on luxury goods at home, encouraged by government measures like import tariffs cuts aimed at boosting domestic spending.
Chinese shoppers account for over a third of sales in the luxury industry as a whole.
Including YNAP and Watchfinder, Richemont's sales were up 24% at constant currencies, in line with average analyst forecasts compiled by Inquiry Financial for Reuters.