"I drew a line at the U.N. They haven't crossed that line, but what they are doing is shortening the time it will take them to cross that line," Netanyahu told the annual meeting of the Conference of Presidents of Major American Jewish Organizations in Jerusalem Monday.
"This has to be stopped for the interest of peace and security for the entire world," he added.
Netanyahu said the only way to stop Iran from achieving nuclear capability is to increase pressure on Tehran and upgrade the sanctions imposed on them by the West, The Jerusalem Post said.
"They have to know that if the sanctions and diplomacy fall, they will face a credible military threat. That is essential, and nothing else will do the job, and it is getting closer," he said.
Iran has denied it is trying to develop nuclear weapons but has refused to allow international inspectors full access to its nuclear facilities. It also has turned down deals to allow Russia to provide it with enriched uranium instead of enriching the material itself.