The incident occurred at the Ayodhya bypass when the yoga guru was on his way to a programme at a private college.
As Ramdev's cavalcade passed through the road, some Congressmen, apparently angry over his remarks, pelted stones at it in which a sub-inspector, Ravi Deheria, was injured, police said.
Denouncing the incident as "height of goondaism," Ramdev said there is no place for violence in a democracy and such things would result in utter chaos.
On his remarks against Singh, Ramdev clarified that he had "not cursed" the Congress leader despite the fact that he (Singh) had termed him a "fraudster".
Asked about his statement against Singh in Raipur, Ramdev claimed that he had not said anything objectionable about the health of the Congress leader or that of his family.
"I only said that because of unnecessary statements, Singh had suffered politically. In fact I advised him that for his healthy and happy future, he should not make such statements," Ramdev said.
He alleged that Congress has no faith in democracy.