"PM called UK PM H.E. @theresa_may to express India's solidarity & conveyed deepest condolences for victims of the terror attack in London," the PMO tweeted.
Modi had yesterday expressed sadness over the killings in the attack and said India stands by the UK in the fight against terror.
"Deeply saddened by the terror attack in London. Our thoughts and prayers are with the victims and their families," Modi had said in a tweet yesterday.
Five people were killed and nearly 40 injured when a terrorist suspect mowed down pedestrians on a bridge and stabbed a police officer close to the British parliament complex in an incident inspired by "international terrorism".
Those dead included the assailant and the policeman he stabbed. The attacker was shot dead by Scotland Yard officers.