We will be issuing a formal demarche to the Chinese government in Beijing on this issue in the coming days, probably early next week, U.S. State Department spokesman P.J. Crowley told reporters.
It will express our concern for this incident and request information from China as to an explanation of how it happened and what they plan to do about it, the spokesman added.
A demarche is a formal communication -- typically delivered in person by a diplomat based oversees to a foreign government -- that sets out his or her country's views, for example to protest against a policy or action.
It can be conveyed orally or in writing.
The senior Washington-based U.S. diplomat for China met with a Chinese diplomat on Thursday to seek an explanation about the cyber attacks and censorship, the State Department said on Thursday.
Google Inc announced on Tuesday it is no longer willing to continue censoring Internet search results in China and that it may shut down the google.cn website and close its offices in the country.
In its statement, Google said that in mid-December it detected a sophisticated and targeted attack on its corporate infrastructure originating from China that led to the theft of intellectual property from the company.
It also said it had evidence suggesting that one of the main goals of the attackers was to access the Gmail accounts of Chinese human rights activists.
(Editing by Philip Barbara)