Russian bantamweight Vladimir Nikitin will not box American Shakur Stevenson after being left bloodied by Conlan.
"The injury suffered by Vladimir is too serious," said Russian official Igor Kazikov.
Stevenson will fight Robeisy Ramirez Carrazana in the final after the Cuban beat Uzbekistan's Murodjon Akhmadaliev.
Nikitin, meanwhile, will still receive a bronze medal.
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Belfast boxer Conlan said after Tuesday's contentious decision that his Olympic dream had "been robbed".
Nikitin's face was badly bloodied after the quarter-final, which most observers felt had been conclusively won by the Irishman.
Immediately after the bout, Conlan made clear his annoyance at the verdict in an expletive-filled live TV interview with Irish broadcaster RTE.
Thursday's development may increase the the pressure on amateur boxing's world governing body, Aiba, which has faced criticism from boxers and coaches in Rio after a number of contentious judging decisions.
On Wednesday, the international body announced that it had dropped a number of officials after a review of their decisions at the Olympics.
Aiba said that, after 239 bouts in Rio, "less than a handful of the decisions were not at the level expected".
The body has admitted it is in a "transition process", but said results of bouts already contested will stand.

The billionaire, who was a prominent backer of Brexit, told the BBC he was "enormously optimistic" about trading with the rest of the world.
His comments came as his engineering firm Dyson reported a 41% increase in profits to £631m.
The popularity of its vacuum cleaners in fast-growing Asian markets was a major reason for the rise.
The company said sales of its products increased by 45% to £2.5bn, helped by growth of 244% in China, 266% in Indonesia and 200% in the Philippines.
The success of new product lines such as hair dryers also fuelled growth.
On Wednesday, Prime Minister Theresa May is due to start the process of the UK leaving the EU.
In an interview with the BBC, Sir James said: "Europe's only 15% of the global market and the really fast-expanding markets are in the Far East.
"I'm enormously optimistic because looking outwards to the rest of the world is very, very important because that's the fast-growing bit."
Sir James Dyson is the poster child for the kind of global-facing confidence the government is keen to harness in a week that it signals the beginning of the end of the UK's membership of the EU.
The entrepreneur has been a prominent supporter of Brexit and remains clear that British business success lies beyond Europe.
He is putting his money where his mouth is - investing £2.5bn, expanding his Wiltshire base by buying 500 acres of old airfield in Hullavington and hoping to double his 3,500 workforce in the next four years.
Critics, though, say that while he designs products in the UK, he manufactures them in the Far East and so his export arrangements may not be subject to the same Brexit uncertainty as for those manufacturing in the UK.
Sir James said it would be possible to remain close to Europe after Brexit, while also forging closer ties with Commonwealth countries.
"I'm a patriot, which is why I'm rather keen on re-connecting with the Commonwealth," he said.
And he rejected the suggestion EU staff could be forced to leave the UK - saying it was "absolute nonsense to suggest countries are going to chuck out foreign citizens".
The entrepreneur, who has criticised the lack of British engineers, also defended his decision to have major operations in Asia, saying the firm's intellectual property and profits were still in the UK.
"I'm resident in England, we pay all our tax here," he added.
Dyson designs many of its products in the UK, but largely manufactures them in Asia.  It has tripled its team in China and recently opened a new £330m research centre in Singapore.
The firm is also opening a new multimillion-pound research centre in Wiltshire, England and a university at its existing Malmesbury campus in the Cotswolds.
The boxer who controversially beat Ireland's Michael Conlan in the Olympic quarter-finals has pulled out of his Olympic semi-final because of injury.
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Sir James Dyson has said UK business success lies beyond Europe because that is where the fastest growth lies.