In an open letter to party volunteers, he, however, claimed that even those who did not vote for the Aam Aadmi Party (AAP) had pledged to vote for it in the Assembly elections because of the various work it has done.
"During the Lok Sabha elections, our volunteers ran a superb campaign putting all their energies into it," Kejriwal said in the letter.
He added that AAP's candidates were among the best.
"The results, however, didn't meet our expectations. Post election ground analysis has revealed two major reasons.
"First, the atmosphere that prevailed in the country rubbed off on Delhi as well. Second, people saw this 'big election' as between (Prime Minister Narendra) Modi and (Congress President) Rahul (Gandhi) and voted accordingly," he said.
Whatever the reason, he added, the AAP was not able to explain to the public why they should vote for AAP in the Lok Sabha battle.
Listing the achievements and initiatives of the AAP government in Delhi, he said people had assured them that in the "small election" for Delhi Assembly, "they will vote in the name of the incredible work we have done in Delhi".
The BJP swept all the seven Lok Sabha seats in Delhi while the AAP finished second in two seats and third in the rest. However, it won one seat in Punjab. In 2014, it won four seats in Punjab and finished at the second spot in all seven Lok Sabha seats in Delhi.
( With inputs from IANS )