In Thursday's call, Trump "reiterated his strong appreciation for the special relationship between the United States and United Kingdom and noted he is looking forward to meeting with the Prime Minister at the G7 Summit in Biarritz, France later this month," the White House said.
The United States is leaning hard on allies to keep out Chinese companies from the fast emerging 5G cellular market, arguing that they pose a security risk.
Earlier last month, US President Donald Trump said that Boris Johnson would do a "great job" as the UK PM.
"I like him," Trump told reporters in the Oval Office.
"He is going to do a great job," the Republican president added. "We get along well."
"He's a different kind of a guy, but they say I'm a different kind of a guy too. We get along well. I think we'll have a very good relationship," Trump told reporters.
Thursday's vote in the Welsh sheep farming community of Brecon and Radnorshire offered a stark choice between a Brexit-backing candidate from Johnson's Conservative party and a Liberal Democrat who wants to preserve Britain's four-decade stay in the EU.
Johnson dropped by the region on Tuesday to help out Chris Davies -- a Conservative MP who was forced to step down after becoming embroiled in an expanses scandal.
Davies protested his innocense and contested the seat again but the Liberal Democrats' Jane Dodds received 13,826 votes to Davies' 12,401 after having two smaller pro-EU parties back her bid.
The result extends a recent revival for the Liberal Democrats at the major parties' expense.
In the call made Thursday, Trump and Johnson discussed "areas of further cooperation, especially relating to trade, 5G, and global security," White House spokesman Hogan Gidley said in a statement.