The Presidency said Buhari has not broken any law that could justify his resignation, adding that he handed over to his competent Vice - Osinbajo - before traveling.
The Senior Special Assistant to the President on Media and Publicity, Garba Shehu, said Buhari has not broken any law that could justify his resignation.
Speaking in an interview with State House correspondents at the Presidential Villa, Abuja, he noted that the President complied with the laws of the land before traveling abroad.
On May 7, 2017, Buhari traveled back to London, the United Kingdom, to receive further medical attention.
The protesters, a coalition of civil society groups, marched to the Villa on Monday, demanding that the President either resumes or resigns.
But Shehu reminded them that Buhari handed over to the Acting President, Yemi Osinbajo, whose performance has been commended by Nigerians and Buhari himself.
He said, "They (the protesters) are only exercising their rights in line with the constitution of this country.
"Of what use or value is a democracy in which citizens cannot embark on peaceful protests? So we respect their right to convene or undertake peaceful protest.
"On the second issue of whether the President should resign or disclose or whatever, I think they are stepping outside the laws of this country.
"Anyone conversant with the constitution of this country would have noticed or seen that Mr. President has complied 100 percent with the requirements of the constitution of this country.
"He has handed over power to the Vice President, relying on the constitution and the Vice President is carrying on with the affairs of this country. He is undertaking activities of government in line with the constitution in a way that the President himself has given words of commendation.
"So, the President has not breached any law. What he has done is perfectly in line with the constitution of this country and people are looking for things to say. I think they should do their research very well."
It is believed that the protest may have been instigated by the opposition, Peoples Democratic Party, whose members and leaders have publicly called for Buhari's resignation.