Jindal, who is currently abroad, has sent a letter to the khap representatives declaring his support on the issue.
"Before leaving India, Jindal signed the letter and we have sent it to the representatives of khap panchayats. Jindal has extended his full support and assured all khaps of every possible assistance," Vivek Mittal, personal secretary to Jindal, told IANS.
Various khap panchayats have launched a widespread campaign seeking an amendment in the Hindu Marriage Act to outlaw marriages within the same gotra.
Verdicts of khap panchayats against people marrying in the same subcaste has led to a spate of "honour killings" in the state. Many couples and their families have also been socially boycotted and forced to leave their homes and land.
The panchayats insist that it's an age old belief that two people of the same subcaste are considered as siblings and cannot marry.
In their meeting at Kurukshetra May 2, the panchayats had appealed to all elected representatives of Haryana to support their demand within a month.
"Jindal has also urged them to fight against other social evils like dowry system and female foeticide plaguing our society. He could not attend the last meeting of khaps due to his tight schedule, but has promised to try his level best to attend forthcoming meetings," Jindal's aide said.
Khap panchayats had earlier announced a siege of Jindal's home in Kurukshetra in case he did not support their demand.
A few days ago, the opposition Indian National Lok Dal (INLD) also agreed to support the demand for an amendment as demanded by the councils.
The demand comes after a Haryana court gave capital punishment in March to five people for an "honour killing".
A Karnal court had sentenced five people to death and one person to life imprisonment for killing a couple who had married despite belonging to the same gotra.
The murdered couple, Manoj, 23, and Babli, 19, had married in 2007 against the wishes of their families.
They were murdered by members of Babli's family.
Defiant khap leaders are headed for a confrontation with the state government and recent rulings of the Punjab and Haryana High Court over illegal decisions on marriages announced by various panchayats.
Khap leaders have proposed to hold another 'mahapanchayat' (grand council) in western Uttar Pradesh's Bijnor district May 14.