Iranian opposition leader Mir Hossein Mousavi said on Thursday he was “under pressure” to withdraw his complaints over the disputed presidential election as the nation struggles to contain its biggest crisis since the 1979 revolution. “The recent pressure on me aims to make me give up my demand for the election to be cancelled,” Mousavi said on his Kalameh website. Mousavi, who lost heavily to incumbent President Mahmoud Ahmadinejad in the June 12 vote according to official results, has complained of widespread irregularities in what he has branded a “shameful fraud.” But Mousavi, who was premier in the aftermath of the 1979 revolution said he would resist the pressure. “I cannot say that white is black and black is white. We should be honest. The solution is not that I say something which I don't believe in.” Mousavi's claim of pressure came as President Ahmadinejad warned his US counterpart Barack Obama to stop meddling in Iran's affairs. “I hope you (Obama) will avoid interfering in Iran's affairs,” Ahmadinejad said, accusing the US leader of using words similar to those of his predecessor George W. Bush. “Will you use this language with Iran (in any future dialogue)? If this is your stance, there will be nothing left to talk about,” said Ahmadinejad. He also took aim at Britain, which Iran has repeatedly accused of fomenting unrest, saying Britain and other European countries were led by “a bunch of politically retarded people.”