"The Islamic Republic of Iran does not hesitate a moment to protect its security and national interests, and will immediately and decisively respond to any possible adventurism,"Foreign Ministry spokesman Khatibzadeh said in a statement published on the ministry's website.
Iran has denied any involvement in the attack on Thursday in which two crew members – a Briton and a Romanian – were killed.
The United States and Britain said on Sunday they would work with their partners to respond to the attack on the Mercer Street, a Liberian-flagged, Japanese-owned petroleum product tanker managed by Israeli-owned Zodiac Maritime.
"Upon review of the available information, we are confident that Iran conducted this attack," US Secretary of State Antony Blinken said in a statement, adding that the attack was carried out using a drone.
Blinken said an "appropriate response" was forthcoming, according to AFP.
British Foreign Secretary Dominic Raab described the attack as "deliberate, targeted and a clear violation of international law by Iran".
Britain summoned the Iranian ambassador on Monday.
"Iranian Ambassador to the UK Mohsen Baharvandwas summoned today to the Foreign, Commonwealth & Development Office," said a British government statement, Reuters wrote.
Khatibzadeh dismissed the US and Britain's statements as "contradictory", and said "if they have any evidence to support their baseless claims, they should provide them".
The spokesman "strongly regretted the baseless accusations" which were "false and provocative".
He also blamed them for effectively supporting "terrorist attacks against and sabotage of Iran's commercial ships" through their "silence".
Israeli Prime Minister Naftali Bennett had accused Tehran of "trying to shirk responsibility" for the attack". Israel's foreign minister said on Sunday the incident deserved a harsh response.
Khatibzadeh said Sunday that Israel "must stop such baseless accusations".
An unnamed Iranian official told the country's Nournews website on Monday that Tehran considered "the threats of Western officials and the Zionist regime (Israel) to be more of a propaganda gesture".
"Washington and London will be directly responsible for the consequences," the official told Nournews, which is close to Iran's Supreme National Security Council.