PSD leader Liviu Dragnea called a largely peaceful anti-government protest of around 100,000 people on August 10 a "failed coup d'etat."
An anti-government protest in Romania in which hundreds of people were injured this month was a failed attempt to overthrow the government, encouraged by the president, the leader of the ruling Social Democrat party said late on Tuesday.
About 100,000 mostly peaceful protesters rallied against the Social Democrat (PSD) government on August 10.
Riot police used a water cannon and tear gas against the crowd and more than 450 people needed medical assistance and dozens were taken to hospital.
Some protesters threw bottles and rocks at riot police but multiple video recordings show police beating non-violent protesters holding their hands up.
"I saw a failed coup d'etat," PSD leader Liviu Dragnea told private television station Antena 3 in his first public appearance since the protest.
Dragnea holds a tight grip over the ruling party but cannot be premier because of a previous conviction in a vote-rigging case. In June, the Supreme Court sentenced him to three and a half years in prison for inciting others to abuse of office. He denied the charges and has appealed the verdict.
Centrist President Klaus Iohannis condemned the disproportionate use of force by police but Dragnea said the criticism undermined police and incited protesters to violence.
Dragnea said he would want to impeach Iohannis, provided he got the support of the junior ruling coalition party ALDE.
More than 380 people and rights groups have filed criminal complaints against riot police since the protest, and prosecutors said they have opened 22 cases.
Anti-government protests have occurred continuously since the Social Democrats took power last year and repeatedly attempted to weaken anti-corruption legislation. On Tuesday, Dragnea accused multinational corporations and banks of financing and encouraging protests.
Anti-corruption group Transparency International ranks Romania among the European Union's most corrupt states and Brussels is keeping its justice system under special monitoring.
Dragnea also said four men tried to kill him in 2017.
"I had an assassination attempt last year, four foreigners came, they were here three weeks. I found out who paid them, but I cannot say the name, a person who is famous in the world."
Asked whether he was thinking about US financier George Soros, he said: "I am not thinking about Soros, he is thinking of me."
A tendency to demonize Soros, a Hungarian-American financier who funds liberal charities and non-governmental organisations worldwide through his Open Society Foundations, is common across Central and Eastern European states such as Hungary and Poland where illiberal democracies are on the rise.