VHP and Shiv Sena activists tried holding a protest at Mr Khan's concert at Shantigram in Adalaj town of Gandhinagar today.
Four persons were today arrested for allegedly demanding money from the organiser of Pakistani singer Rahat Fateh Ali Khan's concert in Gandhinanagar to ensure the event went off "peacefully", police said.
In another development, 35 activists of Shiv Sena and Vishwa Hindu Parishad were detained when they tried to protest at the venue of the concert this evening in the state capital.
"Four persons have been arrested. They were demanding Rs 50,000 to ensure that the programme went off peacefully," Superintendent of Police, Gandhinagar, Virendrasinh Yadav said.
"These accused, claiming to be associated with a little- known outfit 'Hindu Seva Sangathan', had made phone calls to the organisers on several occasions before, and this morning they arrived at the venue seeking money," Mr Yadav said.
"So far we have arrested four persons. We don't know when this outfit was formed. It was probably formed to extort money," Mr Yadav said.
Police lodged an FIR under section 384 (extortion) of the Indian Penal Code on the complaint of the organiser Shanku's Water Park's employee, Hitendra Kumar.
Meanwhile, VHP and Shiv Sena activists tried to protest at Mr Khan's concert at Shantigram in Adalaj town of Gandhinagar district today.
Police said they detained 35 activists, who would be released after the programme is over.
On Monday, the Shiv Sena activists had torn up a large banner announcing the programme. Sena members said they will not allow Pakistani singers to make money in India when Indian soldiers and citizens were getting killed by Pakistan-backed terrorists.
On April 22, the Shiv Sena had staged protest against Pakistani singer Ghulam Ali at Mahuva town in Bhavnagar when he came to collect an award.