Netanyahu also said Iran was behind an attempted bombing outside his country's embassy in Tbilisi, Georgia.
He called called Iran "the greatest exporter of terror in the world."
U.S. Secretary of State Hillary Clinton issued a statement condemning the attack in New Delhi, where the wife of Israel's Defense Ministry's representative to India was hospitalized after a magnetic bomb attached to a car she was in exploded Monday, and the threat in Georgia.
The driver of the car and two others in another car suffered minor injuries in the blast in New Delhi, officials said.
"I condemn in the strongest possible terms the bombing of an Israeli diplomatic vehicle in India and the attempted attack on Israeli Embassy personnel in Georgia," Clinton said.
"The scourge of terrorism is an affront to the entire international community. The United States places a high priority on the safety and security of diplomatic personnel around the world and we stand ready to assist with any investigation of these cowardly actions."
New Delhi Police Commissioner Brajesh Kumar Gupta said the woman, who was heading to pick up her children at the American Embassy school, was conscious and in stable condition.
Netanyahu blamed Iran for the incident inTbilisi, where police defused a bomb attached to a car in the Israeli diplomatic fleet after being alerted by an embassy employee.
Iran has vowed revenge for recent assassinations of scientists involved in the country's nuclear program, and Hezbollah, which receives funding and support from Iran, has said it would avenge the killing of one of its leaders, Imad Moughniyeh, who was killed in a car bombing in Damascus on Feb. 12, 2008.
Netanyahu said recent attempted attacks on Jews and Israelis had been thwarted elsewhere, including Azerbaijan and Thailand.
"In all these cases, the elements behind the attacks were Iran and its proxy, Hezbollah," Netanyahu said
Iran did not immediately respond to the accusations.
Netanyahu said Israel has put its foreign missions on high alert in recent days because of the fourth anniversary of Mughniyah's death.
Israel's Foreign Ministry instructed all of its diplomats not to use their vehicles until they are checked by security officials, and Israelis traveling abroad were advised to avoid certain destinations, including Egypt, Turkey, Azerbaijan, Georgia, Armenia, Ivory Coast, Mauritania and Venezuela.
Foreign Minister Avigdor Lieberman said Israel won't stand for attacks on its diplomats. He said the incidents Monday demonstrated how Israel and its citizens face "physical and diplomatic" terror threats daily, Haaretz said.