Joining the chorus, Nabha slammed Amarinder for going to the press on the issue of indiscipline in party unit, and termed it a "malicious campaign" to "publicly hurt" his image.
Yesterday, Mohindra had expressed his displeasure over Amarinder's statements in the press.
Challenging Amarinder, Nabha said the state party chief has "no authority" to serve such notices.
After defeat in Moga bypoll, Amarinder had reprimanded the two leaders for their "absence" during the campaigning.
The act of serving notices is "unwarranted" at a time when the morale of party workers is "already low", and this may affect party's prospects in 2014 elections, Nabha said.
"I think if you (Amarinder) would have placed your house in order first, the party in Punjab would not have suffered two successive defeats in 2007 and 2012 Assembly elections," Nabha said.