Shein Group Ltd. and Temu saw double-digit sales declines in the week after they raised retail prices to cover the costs of increased US tariffs, an initial sign that Donald Trump’s punitive trade measures have taken a toll on the shopping platforms’ popularity.

Chinese e-commerce giants Shein and Temu are scaling back sales in the North American market as rising tariffs and new trade regulations disrupt their low-cost business models. At the same time, major U.