A row has broken out over attempts by President Mahmoud Ahmadinejad to control Iran's biggest university.
Supporters of Mr Ahmadinejad protested outside parliament on Tuesday after MPs voted down a bill to replace several board members of Azad University.
Parliament speaker Ali Larijani has denounced the protests, reportedly calling them "ugly and vindictive".
Correspondents say the battle for control has revealed new divisions within the country's leadership.
Azad University, a private institution, has 1.5 million students and billions of dollars in assets.
For almost 30 years, it has been considered to be a key centre of support for former President Ali Akbar Rafsanjani, a rival of Mr Ahmadinejad, the BBC's Sebastian Usher reports.
Mr Ahmedinejad's supporters accuse him of allowing Azad's resources to be used by the opposition during last year's election campaign, he adds.
Battle for control
Under the defeated bill, Mr Ahmadinejad had sought to put government-appointed trustees on the board of Azad University in Tehran.
He also sought to block Mr Rafsanjani from transferring the assets of the university to a religious foundation.
But on Sunday parliament rejected Mr Ahmadinejad's proposal.
At the protest following the vote, which was attended by dissenting MPs and students of the university, protesters denounced the "traitor MPs" who voted against the reforms.
Mr Larijani, another rival of Mr Ahmadinejad, called the response ugly and vindictive, the conservative Iranian news agency Mehr reported.
"If the norms are observed in the criticism of [government] branches, it will be good... but [this should] not [be done] with bad language," Mehr quoted him as saying in a speech to parliament.
He warned them that once the bill was ratified by Iran's powerful Guardian Council, they would be expected to respect the law.