Bangkok , Thailand ( CNN ) -- Thousands of Thai riot police faced off against anti-government demonstrators in Bangkok Friday as they attempted to seize sites occupied by protesters for months . Security forces only succeeded in narrowing the areas held by protesters in some parts of the city , but vowed to return to continue their efforts Saturday . The stand-offs passed without serious violence , although a journalist sustained minor injuries when a protester near Government House threw a firecracker . Demonstrators opposed to the government of Prime Minister Yingluck Shinawatra have been camped out since November at sites including Government House -- the office of the prime minister and appointed cabinet ministers -- and the government complex in the Chaengwattana area of Bangkok 's suburbs . But Lt. Gen. Paradon Patthanathabut , Thailand 's national security chief , told CNN that enough was enough . `` Public sentiment now is 'That 's enough . ' It has gone beyond peaceful protest , '' he said . The protesters ' actions were blocking public access to government services , making intervention by authorities necessary , he said . `` We are going to enforce the law against protesters in certain areas . '' While security forces succeeded in seizing only some of the territory held by protesters , he said they would be back tomorrow . `` We have withdrawn our forces and will go back there again tomorrow , '' said Paradon . `` We were there to express our seriousness that we have to retake the area , ( or ) at least open up the roads for public . '' He said he did not expect events to turn violent , saying his approach was to attempt negotiations before sending in teams to retake the area . READ MORE : After disrupting Thailand elections , protesters vow to continue . Protesters have been calling for the ouster of Yingluck , whom they allege is a puppet of her billionaire brother , the deposed , exiled former Prime Minister Thaksin Shinawatra . The protests were sparked in November by her government 's attempt to pass an amnesty bill , that would have paved the way for her brother 's return to the political fray in earnest . Yingluck called general elections on February 2 in an attempt to bring an end to the crisis . But the opposition Democrat Party boycotted the polls and protesters blocked officials from gathering ballots and obstructed voter registration in many constituencies . Thailand 's Constitutional Court ruled this week that there were insufficient grounds to consider a petition filed by lawyer Wiratana Kalayasiri , a former MP for the Democrat Party , seeking the annulment of the elections . READ MORE : Trapped in a gunfight -- CNN producer 's harrowing account of Thai election violence . READ MORE : Thai elections -- the politics of crisis .
Thai police and protesters faced off Friday as authorities attempted to clear protest sites . Parts of Bangkok have been evacuated since November . Police regained some of the positions held by protesters near Parliament House . They promised to return tomorrow to try again .