The United States demanded "clarification" over the result while congratulating "courageous" Congolese voters.
"The National Independent Electoral Commission has announced provisional results, but we await clarification of questions which have been raised regarding the electoral count.
"We urge all stakeholders to remain calm as the process continues," State Department deputy spokesman Robert Palladino said in a statement.
He also noted the "importance of President Joseph Kabila's decision to abide by his constitutionally mandated term limits and transfer power to a successor".
The European Union said it was waiting for the verdict of election monitors.
"We have also noted that these results have been contested by part of the opposition," said EU spokeswoman Maja Kocijancic.
"In the meantime we call on all political actors in DRC to abstain from any kind of act of violence and allow for the democratic process to continue," she said.
France however broke ranks to challenge the official result.
"It really seems that the declared results... are not consistent with the true results," Foreign Minister Jean-Yves Le Drian told CNews television.
"On the face of it, Mr Fayulu was the leader coming out of these elections," he said.
The DRC's Catholic Church, he argued, had reached the same conclusion after garnering data from its 40,000 election observers across the country.
The church itself has so far only said that the official results did not reflect the data its observers collected from polling stations.
It has not published the name of the candidate that, in its view, was the true victor.