Google also notified its Crimean partners that the company would not be able to return money from blocked users' accounts. However, another letter sent later from Google to AdSense users contradicted this, saying that the company would refund all sums exceeding $10.
Earlier on Friday, US-based digital payment system PayPal notified customers in Crimea that it will stop providing services to residents of the peninsula.
In December 2014, US payment giants MasterCard and Visa suspended services to banks in Crimea.
US companies have ceased business activities in the peninsula in the wake of an order issued by US President Barack Obama on December 19, 2014. The order said that US companies must stop supplying products to Crimea by February 1, 2015.
The restrictions specifically targeting Crimea were imposed by Western countries after Crimea's reunification with Russia in March 2014.