U.S. President Donald Trump's former personal attorney, Michael Cohen, said Friday he believes the president is not telling the truth about his campaign's involvement with Russia.Cohen was sentenced Wednesday to three years in prison, in part for helping make payments to two women who alleged they had affairs with Trump to stay silent before the 2016 election.In an interview on ABC's Good Morning America, Cohen responded "no" when asked if Trump was telling the truth to Special Counsel Robert Mueller about "everything related to Russia."Cohen said he bought the silence of the women because Trump "was very concerned about how this would affect the election" if the allegations were made public. Cohen responded "of course" when asked if Trump was aware it was wrong to make the payments, and added the payments were to "help [Trump] and his campaign."Cohen pleaded guilty to arranging $280,000 in payments, at Trump's direction, to adult film star Stormy Daniels and Playboy model Karen McDougal. The payments, however, were not reported as campaign donations.Cohen also pleaded guilty to lying to Congress about Trump's efforts in early 2016 to build a Moscow skyscraper, to mimic Trump's false claim to voters that he had no Russian business ventures. U.S. Deputy White House Press Secretary Hogan Gidley dismissed Cohen's interview, when asked by reporters Friday at the White House."The fact that the media is giving credence to a convicted criminal — you're giving credence to someone who's a self-admitted liar," Gidley said. "For him to say, 'I'm going to start, I'm going to stop lying now, starting now' is somewhat silly."Trump has contended the hush money payments were not criminal. He told Fox News earlier this week the charges were brought by prosecutors "to embarrass me. I never directed him to do anything incorrect or wrong."Prosecutors said that Cohen, at Trump's direction, facilitated the payments, in violation of campaign finance laws, to Daniels and McDougal shortly before the 2016 election. The payments were intended to buy their silence about the alleged liaisons with Trump a decade before he sought the presidency. The prosecutors said American Media knew corporations such as itself were subject to campaign finance laws that forbid payments "made for purposes of influencing an election and in coordination with or at the request of a candidate or campaign." Prosecutors also said American Media did not report the payments to the Federal Election Commission.Campaign finance laws require campaign contributions to be disclosed and bar individual donations of more than $2,700.New York prosecutors say then-candidate Trump was involved in making a $150,000 payment to McDougal through American Media Inc.The company owns the supermarket tabloid National Enquirer. The publication bought McDougal's story of her alleged 2006-2007 affair with Trump with the express purpose of killing it so it would not surface before Election Day in November 2016, to boost Trump's chances of winning the White House. American Media reached a deal with prosecutors to avoid prosecution by fully cooperating with authorities disclosing its role with Trump in making the payment to McDougal.'Blind loyalty'Cohen was sentenced after telling a federal judge that his "blind loyalty" to Trump led him to "cover up his dirty deeds."Legal analysts said the developments could strengthen a potential case against Trump himself if prosecutors were to pursue one, although Justice Department guidelines say that a sitting president cannot be charged criminally until he leaves office.Cohen is the closest figure to Trump sentenced to prison in the wide-ranging investigations of Trump's 2016 campaign, its possible links to Russia and whether Trump, as president, obstructed justice by trying to thwart probes by federal prosecutors in New York and Mueller in Washington.Several other prominent Trump figures, including his former campaign chairman and his first national security adviser, have yet to be sentenced for various offenses.Cohen once bragged that he would "take a bullet" to support Trump. More recently, however, Cohen had turned against Trump and said at his sentencing that working for Trump was a "personal and mental incarceration."Cohen attorney Lanny Davis said that after Mueller completes his investigation, Cohen would cooperate with congressional committees as they consider possible wrongdoing by Trump and his aides. Some Democrats in the House of Representatives have called for Trump's impeachment when they assume control of the chamber next month.Patsy Widakuswara at the White House contributed to this report.