The warning has triggered alarm bells among White House officials who oppose her visit. Six people familiar with the Chinese warnings said they were significantly stronger than the threats that Beijing has made in the past when it was unhappy with US actions or policy on Taiwan.
According to Financial Times, China has publicly threatened “strong measures” if Ms Pelosi proceeds with the planned visit in August.
However, one person said China had expressed “stronger opposition” to the US in private than before, it has been reported.
Several other people familiar with the situation said the private rhetoric went even further by suggesting a possible military response.
US national security adviser Jake Sullivan and other senior National Security Council (NSC) officials oppose the trip because of the risk of escalating tension across the Taiwan Strait, according to two people familiar with the debate.
The NSC declined to comment on whether the administration had urged Ms Pelosi to cancel her trip.
John Kirby, NSC head of strategic communications, said on Friday the NSC team provided “context, facts and geopolitical relevant information”, and that the Speaker made her own decisions.
The controversy over the trip has sparked concern among Washington’s allies who are worried that it could trigger a crisis between the US and China, according to several of the people with knowledge of the situation.
On Wednesday, Mr Biden told reporters at a briefing he expected to speak with Xi within 10 days, but did not specify reasons or topics for a call.
READ MORE: Chechen rebels prepare to topple key Putin ally as civil war looms
Mr Biden recorded a video from the White House balcony telling people: “I’m doing well, getting a lot of work done.
“And, in the meantime, thanks for your concern. And keep the faith. It’s going to be OK.”