The US, Britain and the European Union have in recent weeks publicly warned against vote-rigging and election violence, and also expressed concern over President Muhammadu Buhari's suspension of Nigeria's top judge last month.
Saturday's election will see Buhari stand for a second four-year term against former vice-president Atiku Abubakar in what is expected to be a close race.
Buhari's re-election campaign spokesman Festus Keyamo called the statements from the US and others "notably off-key" and unwelcome.
"Instead of encouraging our country toward credible elections, such statements undermine public confidence," Keyamo said.
"It would appear that these envoys seem to have discredited the election before it has even taken place."
Keyamo's comments come after a key Buhari ally, Kaduna state governor Nasir El-Rufai, said outsiders who intervened in the election "will go back in body bags".
"Nobody will come to Nigeria and tell us how to run our country. We have got that independence and we are trying to run our country as decently as possible," he said.
He later denied calling for violence against foreigners and instead said he only wanted Nigeria's sovereignty to be respected.
Nigeria's last election in 2015 was considered free and fair, but state and local elections as well as earlier presidential polls have been marred by violence and fraud allegations.
In recent weeks, tensions have risen between Buhari's All Progressives Congress (APC) and Abubakar's People's Democratic Party (PDP).
The PDP has accused the government of seeking to rig the vote while the APC has said the opposition party is fomenting unrest.
Last week the US State Department called for a vote "free from outside pressure and intimidation" and said anyone who incites election violence should be "held to account".
The US and Britain have previously said they will impose a visa ban on anyone implicated in vote-rigging or violence.
Last month, Washington, London and the European Union publicly expressed concern over Buhari's move to suspend Walter Onnoghen, the chief justice of the Supreme Court who would have ruled on any election dispute.
Buhari justified the move as necessary given the judge was facing a corruption case before an oversight body.
Compared to 2015, international interest in Nigeria's election has been muted as the US administration focuses on domestic issues and Britain wrestles with its impending exit from the EU.
A British colony until 1960, Nigeria is an ally of both countries which are home to large Nigerian diaspora communities.