India's Home Minister P Chidambaram has said "a well-trained person" carried out Monday's attack that injured an Israeli diplomat in the capital, Delhi.
He said it appeared that a motorcycle rider came from behind and attached an explosive device to the back door of the diplomat's car.
At almost the same time, a bomb beneath an Israeli diplomat's car in Tbilisi, Georgia, was found and defused.
Iran has denied Israeli accusations that it was behind the attacks.
Three other people were injured in the Delhi blast.
"The investigations are on," Mr Chidambaram told reporters after meeting the city police chief and other officials on Tuesday morning.
"We believe it was a very well-trained person who committed the attack and that the target was the Israeli diplomat's wife.
"We believe it was a terrorist attack," he said.
The minister said that the police were scanning the closed-circuit camera footage, "but we have no clear images of the bike or the the biker yet".
Mr Chidambaram said they were "not pointing fingers at anyone or any group yet, but we condemn the attack in the strongest terms".
Indian officials have been in touch with Israeli officials and "we have assured them that India will find the perpetrators", he said.
Earlier, Delhi Police Commissioner BK Gupta said: "Police are on the hunt for the biker, wearing a brown jacket and driving a red-coloured bike, who attached a magnetic device to the Israeli embassy car when it was standing at the Aurangzeb Road red light."
Forensic experts were examining the car to determine what type of explosives had been used, he said.
Mr Gupta said the injured diplomat, who the Israeli defence ministry named as Tal Yehoshua Koren, was on the way to pick up her children from school.
She is in a critical but stable condition, doctors said, with shrapnel injuries and is expected to show improvements over the next few days.
Her driver and two people in a nearby car were also injured in the explosion.
The attack took place near Israel's embassy in a heavily-guarded area of central Delhi, near Prime Minister Manmohan Singh's official residence.
Israeli Prime Minister Benjamin Netanyahu was quick to accuse Iran of being behind both the Delhi and Tbilisi incidents.
"Iran is behind these attacks and it is the largest terror exporter in the world," he said.
He suggested that the militant Islamist Hezbollah movement was also involved.
But Iranian Foreign Ministry spokesman Ramin Mehmanparast rejected Mr Netanyahu's accusation, calling it "psychological warfare against Iran".
"We condemn any terrorist action and the world knows that Iran is the biggest victim of terrorism," he was quoted as saying by the official Irna news agency.
Earlier, Iran's ambassador to India, Mehdi Nabizadeh, had told Irna: "These accusations are untrue and sheer lies, like previous times."
Security at Israeli embassies has been tightened in recent months following warnings of potential attacks, after Iran accused Israel of a series of attacks on its nuclear scientists.
BBC security correspondent Gordon Corera said one of them, Mostafa Ahmadi-Roshan, died last month when motorcyclists placed a "sticky bomb" on his car - a technique similar to that used in previous attacks attributed to the work of Israel's Mossad.
Similarities seen in the Delhi blast could be an indication of the aggressors sending a message that attacks in Tehran will be repaid in kind, he added.