"We are the government, we will not be deterred by any criticisms which are completely unfounded from carrying out our duties," Mugabe said at the youth party meeting.
He added that the opposition risked further violent treatment if they stage more protests.
"If they repeat it they will get arrested and get bashed by the police," he said.
"If they want to fight the police, the police have the right to bash."
He said that following threats by the opposition to press ahead with protests to topple him, police officers would be armed to defend themselves.
Tsvangirai, head of the opposition Movement for Democratic Change (MDC), had been treated for head injuries since Tuesday, two days after he and supporters were arrested in an anti-Mugabe protest.