Protests were launched against Faure Gnassingbe's appointment.
They say the 24 April poll is being held too soon to be fully free.
Supporters of the ruling RPT (Rally of the Togolese People) also held a rally in favour of the polling date.
Togo was plunged into crisis earlier in February after the army installed Faure Gnassingbe as president hours after the death of his father Gnassingbe Eyadema.
Although he promised elections within 60 days, as stipulated by the constitution, this did little to quell protests from African neighbours and beyond.
Organisation
Around 2,000 people attended each demonstration, witnesses said.
Opposition leaders say the 24 April deadline does not give them enough time to mount a proper campaign.
"We will continue to fight for better organisation of the 24 April vote, but we will go to the polls and we ask opposition supporters to go and register on electoral lists," said Leopold Gnininvi of the CDPA opposition party.
Supporters of the government insisted that the elections should take place on the scheduled date.
"We say elections should take place on 24 April - only elections can decide between us," said Robert Assidi, a member of the youth wing of the RPT.
Interior Minister Francois Boko said on Wednesday that a special 3,500 strong special security force would be deployed to ensure candidates would be able move freely in the run-up to the election.
Emmanuel Bob-Akitani, vice president of the Union Forces for Change party, will stand as the main opposition candidate against Faure Gnassingbe.
Togo

The opposition parties in Togo held a demonstration on Saturday to demand a delay in the upcoming elections. The elections to replace the deceased ruler, Gnassingbé Eyadéma, are scheduled to be held on April 24, 2005.

The elections were scheduled after an outpouring of international criticism about the army's installment of the late president's son as the country's new leader. The son, Faure Gnassingbé, initially circumvented the constitutional process for new elections 60 days after the death of a current president, but announced elections after African and European leaders strongly criticized the move.

The opposition is demanding a delay for the election, because they fear they will not be able to carry out a sufficient campaign. The candidates from the two prominent opposition parties, Emmanuel Bob Akitani and Nicolas Lawson, both registered with the election officials despite the view that elections should be delayed. In a demonstration in the nation's capital, Akitani's supporters cheered as the candidate called for better representation on elected bodies — something the government denies is a problem.

The supporters of the current government also held a rally in the city, shouting "No" to the prospect of delaying elections.