Speaking alongside U.S. Secretary of State Mike Pompeo before their meeting, Netanyahu said "the first subject I will raise is Iran, the second subject is Iran and so is the third."
"Iran is increasing its aggression as we speak," he added. "We are actively engaging in countering that aggression."
Israel considers Iran to be its greatest enemy, citing its military entrenchment in neighboring Syria and its support for militant groups across the region. Israel also accuses Iran of trying to develop a nuclear bomb — a charge Iran denies.
Earlier, Netanyahu said the U.S. sanctions were creating political and economic problems for Iran, and that while he has given up on European countries joining in the campaign, there is still a "wide spectrum" of options for ratcheting up the pressure.
Pompeo expressed support for recent protests in Iran, saying "these are people that are seeking freedom and a reasonable way to live, and they recognize the threat that's posed by the kleptocrats who are running the Islamic Republic of Iran."
Netanyahu last year welcomed the U.S. withdrawal from the international nuclear deal with Iran along with subsequent American sanctions. The sanctions, targeting Iran's vital oil sector, have hit the Iranian economy hard.
In recent weeks, Iranian forces have reportedly killed over 200 people in demonstrations against rising fuel prices. Demonstrations have also rocked pro-Iran governments in Lebanon and Iraq, forcing leaders in both countries to resign.
"We're seeing the Iranian empire totter. We see demonstrations in Tehran, demonstrations in Baghdad, demonstrations in Beirut," Netanyahu said earlier. "It's important to increase this pressure against Iranian aggression."
The Israeli leader said he would raise other issues with Pompeo, insisting the strong support shown by the Trump administration creates a rare opportunity for Israel to pursue other initiatives.
He is eager for a political boost at a time when he is facing legal and political struggles at home. Netanyahu last month was indicted on a series of corruption charges, and the country appears to be barreling toward an unprecedented third election in under 12 months.
Netanyahu's visit with Pompeo was their first since the secretary of state announced a new American doctrine last month that does not consider Israeli settlements a violation of international law. It was the latest in a string of diplomatic gifts to Netanyahu by the Trump administration.
The Israeli leader said he was "very grateful" for the statement on settlements.
Netanyahu had earlier said he would discuss his proposal to annex the Jordan Valley, a strategic part of the West Bank. Such a move would draw condemnation from the Palestinians and much of the world and almost certainly extinguish any remaining Palestinian hopes of gaining independence.
The Palestinians seek all of the West Bank, captured by Israel in 1967, as the heartland of their hoped-for state.
Pompeo did not respond to a question about the Jordan Valley.
Netanyahu also said he would discuss a proposed joint defense treaty with the Americans. The talks may also touch on an Israeli initiative to formalize already warming ties with Gulf states, who consider Iran a common enemy, by signing non-belligerency agreements.
There has been no indication that the Gulf states are on board, or that it has even been formally proposed to them.
The Trump administration already has delivered a number of landmark victories to Netanyahu, recognizing contested Jerusalem as Israel's capital and recognizing Israel's annexation of the Golan Heights, which it captured from Syria in 1967.
At the same time, the U.S. has cut hundreds of millions of dollars of aid to the Palestinians while shuttering the Palestinian diplomatic mission in Washington. The Palestinians have severed most ties with the U.S. and pre-emptively rejected a peace plan the Trump administration says it has prepared. It has not said when it will release the plan.
The trip gave Netanyahu a brief respite as he fights for political survival in the wake of two inconclusive elections and a damning corruption indictment.
Neither Netanyahu nor his main rival, former military chief Benny Gantz, has been able to secure a parliamentary majority since September elections. If they cannot find a way out of the crisis by Dec. 11, new elections would be triggered.
Most observers believe a unity government between their parties, which together control a majority of seats in parliament, is the best way out of the crisis. But Gantz and his partners have ruled out a power-sharing rotation with a prime minister accused of serious crimes.
Israel's attorney general last month indicted Netanyahu for fraud, breach of trust and accepting bribes in three separate cases.
It is the first time in Israeli history that a sitting prime minister has been charged with a crime. Unlike mayors or regular ministers, the prime minister is not required by Israeli law to resign if indicted. Netanyahu is vowing to remain in office, where he is best positioned to fight the charges.
But lacking a parliamentary majority, and with the first signs of a rebellion brewing within his own ruling Likud party, he has entered the most uncertain chapter of his lengthy career.