Ahmadinejad, whose return to power sparked the most serious political crisis in the Islamic republic's history, is due to submit his new cabinet next week after being sworn in for a second four-year term on August 5.
"Your colleagues ... must be practically committed to the constitution and leadership, have revolutionary spirit ... adequate experience and expertise," said a letter to Ahmadinejad from 202 MPs that was read out in parliament.
The lawmakers said Ahmadinejad's ministers must meet these conditions if he wanted their "maximum cooperation and effort during the vote of confidence."
Moshen Rezai, one of the losing presidential candidates, added his voice to the demands.
He told the head of parliament in a letter: "you should ask (Ahmadinejad) to use the experienced older officials from the ministries," adding that "the most competent and solid people" should be governing, ILNA news agency reported.
Ahmadinejad has already come under fire from within his own hardline camp over a number of controversial political decisions, with the aftermath of the vote exposing rifts within the ruling elite.
Conservatives were furious after he appointed a controversial aide as his first deputy and then took his time carrying out supreme leader Ayatollah Ali Khamenei's order that he be sacked.
Esfandiar Rahim Mashaie eventually stepped down as first vice president but conservatives were further irked when Ahmadinejad sacked the intelligence minister following a "quarrel" over Rahim Mashaie.
Since then hardliners have repeatedly warned Ahmadinejad to obey Khamenei, who pointedly refused to allow the president to kiss his hand at a ceremony to confirm him in office.
Ahmadinejad, whose new term is expected to see a continuing confrontational tone with the West, has vowed to make "considerable changes" to his government, including the appointment of younger people.
He has also pledged to work to improve the economy, stamp out corruption and combat inflation running at more than 20 percent -- a problem critics say was caused by his own expansionist policies.
One leading conservative lawmaker, Gholam Reza Mesbahi Moghaddam, complained that Ahmadinejad was refusing to consult MPs about possible cabinet members.
"If he did so, it would certainly have a positive impact (in the confidence vote)," he was quoted by the Mehr news agency as saying.
Ahmadinejad, 52, was criticised during his first tenure for frequently reshuffling the cabinet, sacking 10 ministers and two central bank chiefs and retaining inexperienced ministers.
He is unlikely to see any let-up in the opposition campaign over what they say was his fraudulent re-election and the subsequent deadly crackdown on protesters.
"A list of 69 dead and about 220 detained after the election was submitted to a special parliamentary committee," Mousavi aide Alireza Beheshti was quoted as saying by the reformist Sarmayeh newspaper.
Officials have said about 30 people were killed, and Tehran's deputy police chief Ahmad Reza Radan said he had "not heard about 69 people being killed in recent incidents."
Mousavi's camp also criticised members of the Guardians Council, the electoral body that upheld Ahmadinejad's election, saying on his website the turmoil was provoked by their support for the incumbent despite the fraud claims.
Judiciary spokesman Ali Reza Jamshidi said 4,000 people were initially arrested in the crackdown and that 3,700 were released soon after.
Iran has put on trial 110 protesters, including top reformists, a French woman lecturer and local employees of the French and the British embassies for allegedly participating in the unrest.
In London, a Foreign Office spokesman said the trial "rests on a gross misinterpretation of what constitutes legitimate activities for embassies and their foreign and local staff in any country in the world."
London-based rights group Amnesty International urged Iran to let international observers monitor the court proceedings, denouncing it otherwise as a "show trial."
Iran's envoy to Paris said on Tuesday that Frenchwoman Clotilde Reiss could stay in the French embassy in Tehran during the case.
Meanwhile, the French presidency said French-Iranian embassy staffer Nazak Afshar has been freed from the Tehran prison where Reiss is still in custody.
-------------------------------------------------------------------------------------------------------------------------------