Asserting that the government would follow the law, Foreign Secretary Dominic Raab said the government would "look very carefully" at its "interpretation" of the legislation, the BBC reported.
The law is likely to gain royal assent on Monday, and Johnson has been warned he could face legal action if he chooses to flout it.
Raab, however, said the "lousy" legislation has "weakened" the government's negotiating position in Brussels.
"That legislation is lousy, it envisages multiple delays, it would effectively force us to accept conditions from the EU however vindictive, punitive and harsh they may be," he said on Sky News on Sunday.
"We will adhere to the law but we will also - because this is such a bad piece of legislation - want to test to the limit what it actually lawfully requires," he said, terming it "the responsible thing to do".
Chancellor Sajid Javid also said on the BBC that the government "absolutely will not" ask the EU to extend the date of Brexit, adding: "We will leave on 31 October."
Appearing on the Andrew Marr programme, Javid, asked how this would work out, said: "You will have to wait and see what happens because there are a lot of days between now and October 19."
( With inputs from IANS )