Iranian President Mahmoud Ahmadinejad delivers a speech at the parliament in Tehran during his swearing-in Wednesday for his second term as president. (Vahid Salemi/Associated Press)

Iranian President Mahmoud Ahmadinejad told Iranians he will resist any interference with his government as he was sworn into office for a second term on Wednesday amid demonstrations outside.

Ahmadinejad, 53, took the oath of office and pledged to protect the constitution during his inauguration speech in Tehran.

"I hereby swear by the almighty God to protect the system of the Islamic revolution and the constitution. I will spare no effort to safeguard the frontiers of Iran," Ahmadinejad said.

The ceremony capped almost two months of the worst political turmoil in Iran since the 1979 Islamic Revolution.

Tens of thousands of people streamed into the streets to protest Ahmadinejad's controversial 2-to-1 election victory in June. The opposition claims Ahmadinejad's re-election was fraudulent and pro-reform leader Mir Hossein Mousavi was the true winner.

At least 30 demonstrators have been killed in the demonstrations, according to the authorities.

The president did not directly address the massive demonstrations but warned that his government would resist any interference.

"We will not remain silent," he said. "We will not tolerate disrespect, interference and insults."

Opposition leaders boycott inauguration

The Iranian government has accused the U.S. and the West of backing street protests.

In his speech, Ahmadinejad noted that several Western countries had not congratulated him on his election win.

He demanded Iran be on an equal footing with other world powers and denounced foreign interference in his country.

"We must play a key role in the management of the world," he said.

Ahmadinejad said he would be focusing his second term on establishing stronger foreign policy and moving the country's economy forward.

Ahmadinejad urged Iranians to show unity. "We should join hands as we move forward to fulfil our goals."

Top officials and clerics attended the inauguration but it was boycotted by opposition leaders and several moderate legislators. Legislative officials said about 273 of 290 legislators were present at the ceremony.

Ahmadinejad has two weeks to draft a cabinet for approval in parliament.

About 5,000 security force troops were deployed around the Iranian parliament and subway stations in the area were closed during the inauguration.

Opposition groups had called on protesters to again take to the streets on Wednesday but there were no reports of any major demonstrations in Tehran.

Witness accounts indicated hundreds of protesters gathered in streets near the parliament and chanted "death to the dictator" but were quickly dispersed by security troops.

Several demonstrators were detained by police on Wednesday and mobile phones appeared to have been cut off in the area, according to witness reports.

With files from The Associated Press