After defeat in Moga bypoll, Singh had given notices to Mohindra and another party MLA Randeep Singh Nabha for their "absence" during the campaigning.
In a letter written to Singh, copies of which were circulated to the press, Mohindra said: "I decided not to pursue this matter further but your statement in all the newspapers today belittling my personality has precipitated the whole issue."
Stating that the show-cause notice sent to him was "uncalled for", Mohindra said that instead, the state party chief could have sought an explanation from him.
Asserting that the party chief should be leading from the front in maintaining discipline and by going to the media "without waiting" for his reply, Amarinder himself have s "breached the discipline".
Denying various charges made against him, including that he was given duty in Moga elections, Mohindra said that Amarinder has been "ill informed" and needs to "update" himself.
Mohindra said he has apprised the high command in detail about the developments after issuance of the show-cause notices and he is releasing his letter to the press "in order to keep the records straight.