A Turkish banker who was convicted in a billion-dollar conspiracy to violate United States sanctions on Iran was sentenced to 32 months in prison on Wednesday in Manhattan.

The high-profile federal trial of the banker, Mehmet Hakan Atilla, depicted high-level corruption in Turkey, riveted the Turkish public and strained that country’s relations with the United States.

Turkey’s president, Recep Tayyip Erdogan, and other Turkish officials have denounced the case. They claim the evidence was fabricated by followers of an Islamic cleric, Fethullah Gulen, whom Mr. Erdogan accuses of fomenting a failed coup in 2016. Mr. Erdogan even raised the issue with President Trump.

Mr. Atilla, 47, was the deputy general manager for international banking at Halkbank, a Turkish state bank that American prosecutors alleged was at the center of the broad sanctions-evasion scheme.

Prosecutors have alleged that Mr. Atilla and his co-conspirators used Halkbank to “launder billions of dollars-worth of Iranian oil proceeds, ultimately creating a slush fund for Iran to use however it wished — the very harm that U.S. sanctions were put in place to avoid.”

On the eve of sentencing, Mr. Erdogan continued to defend Mr. Atilla. In an interview with Bloomberg News this week, the Turkish president said that Mr. Atilla was innocent of any crime and that Halkbank had also been done “a great injustice.”

“If Atilla is going to be declared a criminal, that would be almost equivalent to declaring the Republic of Turkey a criminal,” Mr. Erdogan said.

Mr. Atilla’s lawyers, seeking leniency for their client, argued that he played a relatively minor role in the scheme, especially compared with Reza Zarrab, a well-connected Turkish-Iranian gold trader who was indicted along with Mr. Atilla and seven other Turkish and Iranian defendants.

Before passing sentence on Wednesday, Judge Richard M. Berman of Federal District Court suggested that he, too, saw the defendant as a relatively minor player in the conspiracy. The judge described him as “a reluctant participant,” one who was “following orders” and was not “a mastermind.”

Mr. Zarrab, 34, who at one point hired Rudolph W. Giuliani and a former United States attorney general, Michael B. Mukasey, to try to negotiate a diplomatic resolution to his case, eventually pleaded guilty and became the chief prosecution witness against Mr. Atilla.

At Mr. Atilla’s trial late last year, Mr. Zarrab testified that he had paid millions of dollars in bribes to Zafer Caglayan, then Turkey’s economy minister, and Suleyman Aslan, the general manager of Halkbank, to facilitate the scheme. (Mr. Caglayan and Mr. Aslan are among the seven other defendants charged in the case, who all remain at large.) Mr. Zarrab also suggested in his testimony that Mr. Erdogan had approved the operation.

United States prosecutors had asked that Mr. Atilla be sentenced to about 20 years in prison. Writing last month to the judge, the prosecutors called Mr. Atilla “an individual of significant status and responsibility at his bank, who was entrusted with designing, and successfully carrying out, the methods by which the scheme was executed.”

The prosecutors added that at a time when the United States and other nations “were engaged in the momentous undertaking of depriving the government of Iran of funding for its malign and deadly activities,” including Iran’s pursuit of nuclear weapons and its support of terrorism, “Atilla was a key player in massively undermining those efforts.”

Follow Benjamin Weiser on Twitter: @BenWeiserNYT

Nate Schweber contributed reporting.