Iran's opposition leader Mir Hossein Mousavi vowed Thursday he will not withdraw his challenge of recent presidential election results, despite intense pressure to do so.

The controversial election, which was won by President Mahmoud Ahmadinejad, has become the flashpoint for days of protests and international condemnation.

Mousavi said he will continue to fight the results, which he maintains were fraudulent, despite what he said are ongoing efforts to isolate and discredit him.

On his official website, Mousavi for the first time discussed what he called his growing post-election difficulties.

He complained of the "recent pressures" on him to end his election challenge and he said he has been "completely restricted" from meeting with people.

Mousavi also said he has been subject to verbal attacks but he vowed to keep pressuring the government over what many Iranians believe was a fixed election.

"I am not ready to withdraw from demanding the rights of the Iranian people," Mousavi said on the site, adding that he was determined to prove electoral fraud had taken place and those responsible were "the main factor for the recent violence and unrest and have spilled the blood of the people."

Government crackdown

On Wednesday, 70 university professors were detained after meeting with Mousavi.

A government crackdown on demonstrators has made it increasingly difficult for protesters to make their voices heard in recent days. At least 17 have been killed in clashes.

On Wednesday, Iranian riot police cracked down on protesters involved in a so-called "illegal rally" near the parliament building in Tehran.

Protesters who gathered near the parliament were beaten back with batons, causing some to flee to another Tehran plaza, Sepah Square, about two kilometers north.

Meanwhile, Ahmadinejad on Thursday accused U.S. President Barack Obama of meddling in the country's affairs, and compared him to his predecessor former president George Bush.

Ahmadinejad lashes out at Obama

Obama has joined other Western leaders in condemning the crackdown on protesters and the media, in Iran.

Ahmadinejad suggested he expected better from Obama.

"We expect nothing from the British government and other Europeans governments, whose records and backgrounds are known to everybody and who have no dignity, but I wonder why Mr. Obama, who has come with the slogan of change, has fallen into this trap, the same route that Mr. Bush took and experienced its ending," Ahmadinejad said in a statement quoted by official media.

Inside Iran, there are signs that support for Ahmadinejad is waning.

Several Tehran newspapers reported Thursday that only 105 of 290 members of parliament showed up to a victory celebration for Ahmadinejad on Tuesday.

Parliament Speaker Ali Larijani was among the no-shows.

"Clearly they (the Iranian government) are targeting Mousavi because he is the figurehead of this opposition movement but there are many, many powerful people in Iran who continue their objection and fundamental disagreement with the way the country is being run," CTV's London Bureau Chief Tom Kennedy reported Thursday.

With files from The Associated Press