WASHINGTON — Rudolph W. Giuliani said on Monday that he provided President Trump with detailed information this year about how the United States ambassador to Ukraine was, in Mr. Giuliani’s view, impeding investigations that could benefit Mr. Trump, setting in motion the ambassador’s recall from her post.

In an interview, Mr. Giuliani, the president’s personal lawyer, described how he passed along to Mr. Trump “a couple of times” accounts about how the ambassador, Marie L. Yovanovitch, had frustrated efforts that could be politically helpful to Mr. Trump. They included investigations involving former Vice President Joseph R. Biden Jr. and Ukrainians who disseminated documents that damaged Mr. Trump’s 2016 campaign.

The president in turn connected Mr. Giuliani with Secretary of State Mike Pompeo, who asked for more information, Mr. Giuliani said. Within weeks, Ms. Yovanovitch was recalled as ambassador at the end of April and was told that Mr. Trump had lost trust in her.

The circumstances of Ms. Yovanovitch’s ouster after a smear campaign engineered in part by Mr. Giuliani were documented during testimony to the House Intelligence Committee, where she was a key witness in impeachment proceedings against Mr. Trump. Mr. Giuliani has made no secret of his role in flagging concerns about Ms. Yovanovitch to Mr. Trump.