Turkish President Recep Tayyip Erdogan denied his involvement with the verdict against Istanbul's Mayor and possible candidate in the next presidential elections Ekrem Imamoglu.

"What is behind the storm sparked by a verdict these past few days? This debate has nothing to do with us - neither with me nor with our nation," Erdogan said on Saturday.

A Turkish court sentenced Ekrem Imamoglu on Wednesday to more than two years in prison and prevented him from practicing politics for the same period, including running for next year's presidential elections, on charges of insulting members of the Supreme Electoral Council in 2019.

Imamoglu's team immediately vowed to appeal against his conviction in a case stemming from a remark he made after defeating President Recep Tayyip Erdogan's ally in a hugely controversial 2019 mayoral vote.

"We laugh at all the false words uttered so surely" by those considering the sentence as a political move, Erdogan added.  

"But we are sad to see that some are trying to conduct their games of thrones through us."

The Istanbul Mayor is among a handful of opposition leaders that polls show could beat Erdogan in a head-to-head race in next June's presidential vote.

Thousands of Turks gathered in a square in the center of Istanbul on Thursday to protest the political ban against the opposition mayor of the city, Ekrem Imamoglu, before next year's presidential elections.

This comes six months before the elections in which the Turkish opposition is putting its best foot forward to oust President Recep Tayyip Erdogan, who has ruled the country for 20 years, while a prison sentence against Imamoglu has raised the risk of a presidential struggle between opposition poles.

Turkey's fractious opposition is struggling to unite behind a single candidate to challenge Erdogan in the upcoming elections. 

The sentence targeting the opposition leader stirred up a wave of international criticism.

The US State Department expressed that it is "deeply troubled and disappointment" at the possibility of excluding one of President Recep Tayyip Erdogan's biggest rivals from the political scene.

Germany described the decision as "a heavy blow to democracy," while France urged Turkey "reverse its slide away from the rule of law, democracy, and respect for fundamental rights."