Mr Iohannis said Romania could end up like Poland which faces censure from Brussels over controversial constitutional changes deemed illegal by the EU.
Romania’s ruling coalition plans to push ahead with changes to the legal system despite the bitter dispute between Warsaw and the EU which claims Poland’s constitutional court has been disempowered by the overhaul and judges demoted to agents of the ruling PiS party.
When asked if Romania could face similar sanctions to Poland, Mr Iohannis said: “That risk exists.
“If someone thinks that changing justice laws will not have any consequences, then that person has just fallen from the moon.
“The consequences will depend on the gravity of the changes.”
The Senate has adopted amendments to a law regulating the status of judges and prosecutors, including new sanctions against judges and prosecutors thought to have acted in bad faith.
Critics of the legislation, including opposition politicians, argue that this could compromise the independence of the judiciary.
Attempts by the ruling Social Democrats (PSD) and their liberal junior coalition partner ALDE to change justice laws led to the biggest protests Romania has seen since the fall of Communism in 1989 earlier this year, which have resumed on a smaller scale in recent weeks.
Mr Iohannis spoke as EU chiefs prepared to punish Poland by stripping it of its voting rights as they step up their fight against the eastern European state.
The European Commission is now closer to taking the unprecedented step of triggering Article 7 – the so-called nuclear option – after Poland repeatedly ignored threats and requests for dialogue over controversial policies.
Warsaw’s ruling Law and Justice party (PiS) is overhauling Poland’s constitutional court to bring more control to the government.
The EU is concerned Poland is undermining democratic checks and balances and on Wednesday launched an unprecedented process to suspend Poland’s voting rights in the European Union.
Polish ruling Law and Justice (PiS) party spokeswoman said the move was a “political decision”.
Beata Mazurek said: “This decision has no merit, it is in our opinion solely a political decision.”