By Nicholas Vinocur
PARIS, April 18 (Reuters) - French President Francois Hollande's government called on Thursday for an end to violent protests against a same-sex marriage bill being debated in parliament, warning those behind a rise in homophobic assaults would be punished.
Hollande's initiative to allow same-sex couples to tie the knot - the most significant social reform undertaken since France banned the death penalty in 1981 - has split the nation and sparked huge protests both for and against the law.
As the lower house of parliament prepares for a final vote on the law next week, the "anti" protests have turned violent and police have noted a rise in homophobic assaults.
In one such attack, a gay bar in the northern city of Lille was trashed on Wednesday night by four men shouting homophobic insults, leaving several people with injuries.
"I cannot accept ... homophobic acts and violence against property in the midst of protests, or any defiance of law enforcement officials," Hollande told reporters during a visit to Paris Charles de Gaulle airport.
"(Democratic) procedures must be respected, sensibilities must be respected, and everyone must be heard ... But the law and parliament also need to be respected," he added.
The four Lille assailants were detained by police after they smashed the bar's windows, hurled furniture and yelled insults, starting an altercation that left the assailants, the bar's owner and two bar tenders with light injuries.
The assault came days after the photograph of a gay man whose face was bruised and lacerated after a severe beating in Paris became a viral sensation on social media web sites.
"They came to beat up gays - that's exactly how they phrased it," said the proprietor of the bar in Lille.
Interior Minister Manuel Valls issued warnings by name on Thursday to four far-right groups he accused of inciting hatred against gays on the Internet and seeking to intimidate parliamentarians who support the bill.
Last week three police officers were hurt and two vehicles damaged in scuffles with anti-gay marriage protestors near Paris' Champs Elysees avenue. Twelve protestors were arrested and charged with deliberate violence.
Extra riot police will be deployed at another big march set for Sunday after recent rallies turned ugly. Two lawmakers have received anonymous death threats due to their support for the law, Valls said.
"Law enforcement and intelligence services are mobilised against this situation," Valls said. "There can be no violence against the police, there can be no violence against individuals, there can be no death threats." (Reporting By Nicholas Vinocur and Emmanuel Jarry; Editing by Catherine Bremer and Jon Hemming)