John Dowd, who at the time was heading Mr. Trump’s legal team, at the start of the year told associates of the president he wanted to direct money from the legal defense fund set up for White House officials and campaign aides to the lawyers for Messrs. Manafort and Gates, according to people familiar with the matter. The pair had pleaded not guilty to charges of tax, bank and lobbying violations in the fall of 2017.

That idea was rebuffed by ethics advisers in the White House, the people said. The fund had been set up specifically to aid those who faced legal fees stemming from their involvement with the president. While the charges facing Messrs. Manafort and Gates had stemmed from Special Counsel Robert Mueller’s investigation, they pertained to activities that predated the Trump campaign, making the two aides ineligible for those funds.

On Feb. 22, Mr. Dowd told associates of the president in an email that Messrs. Manafort and Gates needed funds immediately, according to people familiar with the matter. He said he planned to donate $25,000 to Mr. Manafort’s legal defense fund the next day.