There has been an often furious debate among Iranian lawmakers over whether to join the international Financial Action Task Force (FATF), which requires members to pass numerous laws against terrorism financing and money-laundering.
Iran and North Korea are currently the only countries on the FATF black-list, adding to their difficulties in accessing global banking.
But many conservative lawmakers argue the new laws -- in the works since last year -- will cut off Iranian support to Lebanese Hezbollah and Palestinian Hamas -- whose military wings are designated as terrorist organisations by the United States and European Union, among others.
They say the legislation will also condemn members of the Revolutionary Guards listed as terrorists by the US, including the head of its external operations, Qassem Soleimani.
But Abbas Araghchi, deputy foreign minister, defended the efforts to join the FATF, saying it was firmly in Iran's interests.
"This very parliament was the victim of Daesh (the Islamic State group) terrorism this time last year... Without international cooperation and joining international conventions, it is impossible to confront it," said Aragchi.
"Inside the country there are some holes and weaknesses in banking networks, which unfortunately facilitates terrorist groups and drug-smuggling," he added.
The Islamic State group (IS) carried out twin attacks last June on Iran's parliament and the tomb of revolutionary founder Ruhollah Khomeini, killing 17.
Iran, a majority Shiite country, is considered a primary enemy by Sunni jihadist groups such as Al-Qaeda and IS -- and has directly fought these groups in Syria and Iraq.
But with the US pulling out of the 2015 nuclear deal last month and ordering full sanctions to be reimposed on Iran, many say it is pointless to join the FATF.
The other parties to the nuclear deal -- Britain, France, Germany, China and Russia -- are working to salvage the deal and maintain trade ties, but most international banks already refuse to work with Iran for fear of US penalties.
On Sunday, lawmakers voted 138 to 103 (with six abstentions) on suspending the discussion around the Terrorism Financing Convention for two months, while they wait to see how the nuclear deal discussions play out, according to ISNA.