The leader of the pro-Kurdish opposition HDP has accused the ruling AKP of orchestrating nationalist attacks and pushing Turkey towards civil war.
No-one has been killed, but Selahattin Demirtas said "we are facing a campaign of lynching". Violence between the army and the militant Kurdish PKK has escalated in eastern Turkey since a ceasefire collapsed in July.
The country will hold elections in November after inconclusive polls in June.
As the atmosphere in Turkey becomes increasingly febrile, Mr Demirtas questioned whether the vote could even go ahead while temporary military zones were in place in 100 areas of Turkey's mainly Kurdish south-east. He said there had been 400 attacks on HDP offices in two days.
Prime Minister Ahmet Davutoglu took to Twitter to denounce the attacks. "It is unacceptable to damage media institutions, political party buildings and the property of our civilian citizens," he said.
But Mr Demirtas accused the prime minister and President Recep Tayyip Erdogan of taking "the decision to start this war and intensify it".
The HDP denies claims by nationalists that is a political wing of the militant PKK (Kurdistan Workers' Party) and its leaders have accused the ruling AK Party of stoking unrest to drum up nationalist support ahead of the November 1 vote.
The HDP entered parliament for the first time in June elections; its 14pc share of the vote deprived the AKP of a parliamentary majority.
Over the summer, the AKP made a vain attempt to reach a coalition deal with rival parties.
Two newspapers, Hurriyet and Daily Sabah, were also attacked.
Hurriyet had earlier been accused by President Erdogan of misquoting him.
Although no-one has been killed in nationalist protests, dozens of members of security forces as well as militants have died in recent days.
Fourteen police lost their lives in a bomb attack on a minibus near the eastern border on Tuesday, a day after 16 soldiers were killed in another PKK bombing.
Turkish fighter jets launched a wave of attacks on PKK bases in northern Iraq and ground forces crossed the border in pursuit of Kurdish militants for the first time since a ceasefire with the PKK two years ago.
In the south-eastern city of Cizre, one resident told the BBC that a curfew imposed after deadly clashes meant that people were being kept under siege by security forces.
The body of a 10-year-old boy killed in the violence was being kept in a refrigerator by family members because restrictions on movement meant they could not take him to the mortuary.