Trump took to Twitter after John Lewis (above), 76, questioned the legitimacy of the Republican billionaire's White House victory because of alleged Russian interference, before announcing he would not be attending his presidential inauguration on 20 January.
It's the first time Lewis has said he would not attend an inauguration in more than 30 years in office as a Democratic congressman in Georgia.
Congressman John Lewis should spend more time on fixing and helping his district, which is in horrible shape and falling apart (not to......— Donald J. Trump (@realDonaldTrump) January 14, 2017
mention crime infested) rather than falsely complaining about the election results. All talk, talk, talk - no action or results. Sad!— Donald J. Trump (@realDonaldTrump) January 14, 2017
Many have taken offence to Donald Trump's accusations against Lewis, given that he had his skull fractured during the famous Martin Luther King Jr civil rights march in Selma, Alabama, more than 50 years ago.
Lewis has since devoted his life to the non-violent promotion of equal rights for African-Americans.
He also holds a degree in Religion and Philosophy from Fisk University and is a graduate of the American Baptist Theological Seminary.
The congressman told NBC: "You know, I believe in forgiveness. I believe in trying to work with people. It will be hard.
"I don't see this president-elect as a legitimate president. I think the Russians participated in helping this man get elected. And they helped destroy the candidacy of Hillary Clinton."
The comments refer to claims the Kremlin hacked the Democratic Party's computer networks in order to help Donald Trump win. Both the president-elect and the Russian government deny the allegations.
The president-elect later toned down his criticism of Lewis, tweeting:
Congressman John Lewis should finally focus on the burning and crime infested inner-cities of the U.S. I can use all the help I can get!— Donald J. Trump (@realDonaldTrump) January 15, 2017
The fury against Donald Trump coincided with the start of a week of equality protests in Washington DC, which began on Sunday. Thousands have been attending the rallies.
Sunday's protest was led by Rev Al Sharpton, who said: "We come to say to the Democrats, in the Senate and in the House [of Representatives], and the moderate Republicans, to get some backbone - get some guts."