"The news was completely false and mischievously planted in the media," Ms Swaraj tweeted this morning.
She had earlier posted that "there is no dearth of talent in my ministry. I have the assistance of very able Secretaries."
Reports on Monday had said the minister - who made a statement in both houses warning Pakistan over the death sentence - requested Mr Tharoor to help draft the resolution to be adopted in both houses.
"This is a matter that affects us all," Mr Tharoor told NDTV.
"There is no evidence of wrongdoing by (Kulbhushan) Jadhav. If anything, he is the victim of a plan that seeks to cast aspersions on India to deflect international attention from Pakistan's well-known record of sponsoring and supporting terrorism," Ms Swaraj said in her statement, warning Pakistan's government to "consider the consequences for our bilateral relationship if they proceed on this matter."
"Under these circumstances, we have no choice but to consider this sentence, if carried out, as an act of pre-meditated murder," the minister said, calling the Pakistani military court's charges against Mr Jadhav, 46, "concocted."
"The government and the people of India would view very seriously the possibility that an innocent Indian citizen is facing the death sentence in Pakistan without due process and in violation of basic norms of law, justice and international relations," Sushma Swaraj said.
Get Breaking news, live coverage, and Latest News from India and around the world on NDTV.com. Catch all the Live TV action on NDTV 24x7 and NDTV India. Like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.