As many as 122 parliamentarians of Wickeremesinghe's United National Party, Janatha Vimukthi Peramuna (JVP) and Tamil National Alliance last month filed a petition in the Court of Appeal challenging Rajapaksa's authority as the prime minister.
The court issued its order on Monday after 122 members of Sri Lanka's parliament, who are allied with ousted prime minister Ranil Wickremesinghe, filed a legal action on November 23 challenging Rajapaksa's authority as prime minister.
"The damage that will be posed by temporarily restraining a lawful cabinet of ministers from functioning would be ... outweighed by the damage that would be caused by allowing a set of persons who are not entitled in law to function as the prime minister or the cabinet of ministers", judge Preethipadhman Surasena said.
On Tuesday, he reiterated the stance at his Sri Lanka Freedom Party (SLFP) convention, claiming that Mr. Wickremesinghe was "not suitable" for the country.
Wickremesinghe says his dismissal is invalid because he still holds a majority in the 225-member Parliament.
Sirisena plunged the island nation into political chaos by unexpectedly replacing Wickremesinghe with Rajapaksa in late October.
Their position "was that Rajapakse had no legitimacy after losing two no-confidence motions", lawyer and legislator M. A. Sumanthiran told reporters after the decision. "I still hold the majority of the house".
Sri Lanka lies in limbo this week as a court prevents disputed Prime Minister Mahinda Rajapaksa and his disputed Cabinet from holding office. "We are preparing papers to go to the Supreme Court first thing in the morning tomorrow".
Mr. Sirisena's snap decision, compounded by his lawmakers' questionable actions in Parliament since, has prolonged the political turmoil for weeks.
The camp has also suffered two setbacks in the courts, with the Supreme Court staying Mr. Sirisena's dissolution of Parliament and the appeal court restraining Mr. Rajapaksa. The apex court is expected to deliver its verdict on Friday or the following week.