The US government has not banned Coinbase, nor have any major US regulatory bodies. However, some state-level regulators have taken action against Coinbase.
In 2016, the New York State Department of Financial Services (DFS) fined Coinbase $75,000 for failing to obtain a BitLicense, which is required to operate a digital currency exchange in New York. In January 2018, the DFS issued a cease-and-desist order against Coinbase for operating an unlicensed money transmission business.
While the US government has not taken any formal action against Coinbase, it is important to note that some state-level regulators have taken steps to crack down on the popular digital currency exchange. It is possible that more regulation could be coming down the pipeline, so investors and users should keep an eye on developments in this area.