According to the Wall Street Journal, US Ambassador Richard A. Grenell sent a letter to the German economy minister, which said that Berlin should discriminate against Chinese companies like Huawei when selecting providers of 5G equipment to upgrade its networks.
Along with most European countries, Germany's security agencies are heavily reliant on USA intelligence to fight terrorism.
Huawei has repeatedly denied it is an agent of the Chinese government.
"An official from the German Economic Ministry dismissed the letter from Grenell, saying that it included no new information and reiterating that there was no evidence to support USA claims that Huawei posed a risk", Asia Times reported on Monday.
Germany had announced on March 7 that it wouldn't stop any company from bidding on 5G communications contracts.
The US has been lobbying its allies to boycott Huawei due to national security risks.
North Atlantic Treaty Organisation forces would stop communicating with their German colleagues if Berlin teams up with Chinese firm Huawei for its super-fast 5G telecom infrastructure, US General Curtis Scaparrotti warned on Wednesday. Pence accused Huawei to be connected with Chinese intelligence and thus, being capable of becoming a potential threat to the national security.More news: Minnesota Vikings sign Anthony Barr: Grade, reaction and more
"Because 5G networks are largely software-defined, updates pushed to the network by the manufacturer can radically change how they operate", Marquis told CNN.
Neither the US State Department, the German economics minister nor Huawei immediately responded to requests for comment.
However, the Journal reported that a spokesman at the German Economic Ministry said the concerns were not new, and they had seen no evidence that they were true.
Grenell said in his letter that Chinese companies, under Chinese law, can be required to support China's security agencies and that inspections of Huawei software could not ensure there were no vulnerabilities, the newspaper said.
The U.S. clash with Huawei includes a deep disagreement over the arrest in Canada and possible extradition of Huawei CFO Meng Wanzhou, who is also the founder's daughter.
The company's 5G equipment is reputed to be much further advanced than those of rivals Ericsson and Nokia, which has made it attractive for mobile operators looking to quickly roll out new networks.