"The actions taken on November 3 are unacceptable to us. We condemn them and want them to be rolled back," Sharif said.
"NO GOING BACK"
Musharraf won re-election in a vote by legislators on October 6 and later suspended the constitution, declared emergency rule and purged the Supreme Court to block opposition legal challenges to his victory while still a serving officer.
The opposition is still challenging his grip on power.
Protesting lawyers clashed with police in Lahore as Musharraf was being sworn in.
"Our battle is to block military intervention for ever," said Syed Mohammad, president of the Lahore bar association, as lawyers and police started pelting each other with stones.
Black-suited lawyers have been at the forefront of opposition since Musharraf tried to dismiss the chief justice in March.
Referring to threats to boycott the election, Musharraf said no one would be allowed to derail it.
"There is no going back, there is no change. So, anyone who is talking of boycott, should hear this out," he said, adding that the elections must be fair, free and transparent.
Musharraf, who cited rising militancy when he imposed the emergency, also said the military had "broken the back of the spread of terrorism" from remote tribal lands on the Afghan border into so-called settled areas.
"We have to defeat terrorism, there is no choice. Failure is not an option," he said, hours after five soldiers were killed in a blast near the Afghan border.
Ordinary Pakistanis welcomed Musharraf's departure from the army and some said it was time he left politics altogether.
"It's not a good thing for Musharraf to remain in office. He thinks everything is about him, that no one can interfere, that he is the king," said Hafiz Wahab Siddiqui, a 20-year-old business administration student in Lahore.
"He follows American rule. He is a servant of America."
