President Obama said Friday that “Iran is on notice” regarding its nuclear efforts, and that the international community is united in its opposition to Tehran’s nuclear program.

“Iran is on notice that, when we meet with them on October 1, they are going to have to come clean and they are going to have to make a choice: Are they willing to go down the path to greater prosperity and security for Iran — giving up the acquisition of nuclear weapons and deciding that they are willing to abide by international rules and standards in their pursuit of peaceful nuclear energy, or will they continue down a path that is going to lead to confrontation,” he said in a news conference at the G-20 meeting here.

Obama’s comments came hours after Iran acknowledged the existence of a second uranium enrichment facility and ahead of next week’s planned meeting between Iran and the five permanent United Nations Security Council members, plus Germany. The October 1 meeting will take place in Geneva, Switzerland.

Obama said he would not speculate on any course of action absent a satisfactory response from Iran.