Singh called up SP chief Mulayam Singh Yadav and his son Akhilesh Yadav to congratulate them on the party's performance in the Uttar Pradesh polls, the Prime Minister's Office said.
Samajwadi Party got a convincing majority in the elections to the 403-member House.
He also spoke to Punjab Chief Minister Parkash Singh Badal, whose party Akali Dal retained power.
Singh also talked to Goa BJP leader Manohar Parrikar after the party emerged clear victor in the polls.
The prime minister also called up Manipur Chief Minister Ibobi Singh to congratulate him for the Congress' victory.
Ibobi Singh led the Congress in retaining power in Manipur for the third consecutive time with a clear majority.